Web Tech Mod 1 Flashcards
History of web
Sir Tim Berners-Lee is a British computer scientist. He was born in London, and his parents were early computer scientists, working on one of the earliest computers.Growing up, Sir Tim was interested in trains and had a model railway in his bedroom. He recalls:“I made some electronic gadgets to control the trains. Then I ended up getting more interested in electronics than trains. Later on, when I was in college I made a computer out of an old television set.”After graduating from Oxford University, Berners-Lee became a software engineer at CERN, the large particle physics laboratory near Geneva, Switzerland. Scientists come from all over the world to use its accelerators, but Sir Tim noticed that they were having difficulty sharing information.“In those days, there was different information on different computers, but you had to log on to different computers to get at it. Also, sometimes you had to learn a different program on each computer. Often it was just easier to go and ask people when they were having coffee…”, Tim says.Tim thought he saw a way to solve this problem – one that he could see could also have much broader applications. Already, millions of computers were being connected together through the fast-developing internet and Berners-Lee realised they could share information by exploiting an emerging technology called hypertext.In March 1989, Tim laid out his vision for what would become the web in a document called “Information Management: A Proposal”. Believe it or not, Tim’s initial proposal was not immediately accepted. In fact, his boss at the time, Mike Sendall, noted the words “Vague but exciting” on the cover. The web was never an official CERN project, but Mike managed to give Tim time to work on it in September 1990. He began work using a NeXT computer, one of Steve Jobs’ early products.By October of 1990, Tim had written the three fundamental technologies that remain the foundation of today’s web (and which you may have seen appear on parts of your web browser):HTML: HyperText Markup Language. The markup (formatting) language for the web.URI: Uniform Resource Identifier. A kind of “address” that is unique and used to identify to each resource on the web. It is also commonly called a URL.HTTP: Hypertext Transfer Protocol. Allows for the retrieval of linked resources from across the web.Tim also wrote the first web page editor/browser (“WorldWideWeb.app”) and the first web server (“httpd“). By the end of 1990, the first web page was served on the open internet, and in 1991, people outside of CERN were invited to join this new web community.As the web began to grow, Tim realised that its true potential would only be unleashed if anyone, anywhere could use it without paying a fee or having to ask for permission.He explains: “Had the technology been proprietary, and in my total control, it would probably not have taken off. You can’t propose that something be a universal space and at the same time keep control of it.”So, Tim and others advocated to ensure that CERN would agree to make the underlying code available on a royalty-free basis, forever. This decision was announced in April 1993, and sparked a global wave of creativity, collaboration and innovation never seen before. In 2003, the companies developing new web standards committed to a Royalty Free Policy for their work. In 2014, the year we celebrated the web’s 25th birthday, almost two in five people around the world were using it.Tim moved from CERN to the Massachusetts Institute of Technology in 1994 to found the World Wide Web Consortium (W3C), an international community devoted to developing open web standards. He remains the Director of W3C to this day.The early web community produced some revolutionary ideas that are now spreading far beyond the technology sector:Decentralisation: No permission is needed from a central authority to post anything on the web, there is no central controlling node, and so no single point of failure … and no “kill switch”! This also implies freedom from indiscriminate censorship and surveillance.Non-discrimination: If I pay to connect to the internet with a certain quality of service, and you pay to connect with that or a greater quality of service, then we can both communicate at the same level. This principle of equity is also known as Net Neutrality.Bottom-up design: Instead of code being written and controlled by a small group of experts, it was developed in full view of everyone, encouraging maximum participation and experimentation.Universality: For anyone to be able to publish anything on the web, all the computers involved have to speak the same languages to each other, no matter what different hardware people are using; where they live; or what cultural and political beliefs they have. In this way, the web breaks down silos while still allowing diversity to flourish.Consensus: For universal standards to work, everyone had to agree to use them. Tim and others achieved this consensus by giving everyone a say in creating the standards, through a transparent, participatory process at W3C.New permutations of these ideas are giving rise to exciting new approaches in fields as diverse as information (Open Data), politics (Open Government), scientific research (Open Access), education, and culture (Free Culture). But to date we have only scratched the surface of how these principles could change society and politics for the better.In 2009, Sir Tim co-founded the World Wide Web Foundation with Rosemary Leith. The Web Foundation is fighting for the web we want: a web that is safe, empowering and for everyone.
What is Internet?
The Internet is essentially a global network of computing resources. You can think of the Internet as a physical collection of routers and circuits as a set of shared resources.Some common definitions given in the past include −A network of networks based on the TCP/IP communications protocol.A community of people who use and develop those networks.
What are some Internet-Based Services
Some of the basic services available to Internet users are −Email − A fast, easy, and inexpensive way to communicate with other Internet users around the world.Telnet − Allows a user to log into a remote computer as though it were a local system.FTP − Allows a user to transfer virtually every kind of file that can be stored on a computer from one Internet-connected computer to another.UseNet news − A distributed bulletin board that offers a combination news and discussion service on thousands of topics.World Wide Web (WWW) − A hypertext interface to Internet information resources.
What is WWW?
WWW stands for World Wide Web. A technical definition of the World Wide Web is − All the resources and users on the Internet that are using the Hypertext Transfer Protocol (HTTP).A broader definition comes from the organization that Web inventor Tim Berners-Lee helped found, the World Wide Web Consortium (W3C): The World Wide Web is the universe of network-accessible information, an embodiment of human knowledge.In simple terms, The World Wide Web is a way of exchanging information between computers on the Internet, tying them together into a vast collection of interactive multimedia resources.
What is HTTP?
This protocol is used to transfer hypertexts over the internet and it is defined by the www(world wide web) for information transfer. This protocol defines how the information needs to be formatted and transmitted. And, it also defines the various actions the web browsers should take in response to the calls made to access a particular web page. Whenever a user opens their web browser, the user will indirectly use HTTP as this is the protocol that is being used to share text, images, and other multimedia files on the World Wide Web. Note: Hypertext refers to the special format of the text that can contain links to other texts.
What is URL?
URL stands for Uniform Resource Locator, and is used to specify addresses on the World Wide Web. A URL is the fundamental network identification for any resource connected to the web (e.g., hypertext pages, images, and sound files).A URL will have the following format −protocol://hostname/other_informationThe protocol specifies how information is transferred from a link. The protocol used for web resources is HyperText Transfer Protocol (HTTP). Other protocols compatible with most web browsers include FTP, telnet, newsgroups, and Gopher.The protocol is followed by a colon, two slashes, and then the domain name. The domain name is the computer on which the resource is located.Links to particular files or subdirectories may be further specified after the domain name. The directory names are separated by single forward slashes.
What is Website?
Currently you are on our website Tutorialspoint.com which is a collection of various pages written in HTML markup language. This is a location on the web where people can find tutorials on latest technologies. Similarly, there are millions of websites available on the web.Each page available on the website is called a web page and first page of any website is called home page for that site.
What is Web Server?
The term web server can refer to hardware or software, or both of them working together.On the hardware side, a web server is a computer that stores web server software and a website’s component files. (for example, HTML documents, images, CSS stylesheets, and JavaScript files) A web server connects to the Internet and supports physical data interchange with other devices connected to the web.On the software side, a web server includes several parts that control how web users access hosted files. At a minimum, this is an HTTP server. An HTTP server is software that understands URLs (web addresses) and HTTP (the protocol your browser uses to view webpages). An HTTP server can be accessed through the domain names of the websites it stores, and it delivers the content of these hosted websites to the end user’s device.At the most basic level, whenever a browser needs a file that is hosted on a web server, the browser requests the file via HTTP. When the request reaches the correct (hardware) web server, the (software) HTTP server accepts the request, finds the requested document, and sends it back to the browser, also through HTTP. (If the server doesn’t find the requested document, it returns a 404 response instead.)To publish a website, you need either a static or a dynamic web server.A static web server, or stack, consists of a computer (hardware) with an HTTP server (software). We call it “static” because the server sends its hosted files as-is to your browser.A dynamic web server consists of a static web server plus extra software, most commonly an application server and a database. We call it “dynamic” because the application server updates the hosted files before sending content to your browser via the HTTP server.For example, to produce the final webpages you see in the browser, the application server might fill an HTML template with content from a database. Sites like MDN or Wikipedia have thousands of webpages. Typically, these kinds of sites are composed of only a few HTML templates and a giant database, rather than thousands of static HTML documents. This setup makes it easier to maintain and deliver the content.
What is Web Browser?
Web Browsers are software installed on your PC. To access the Web you need a web browsers, such as Netscape Navigator, Microsoft Internet Explorer or Mozilla Firefox.Currently you must be using any sort of Web browser while you are navigating through my site tutorialspoint.com. On the Web, when you navigate through pages of information this is commonly known as browsing or surfing.We will see different type of Web browsers in a separate chapter.
What is SMTP Server?
SMTP stands for Simple Mail Transfer Protocol Server. This server takes care of delivering emails from one server to another server. When you send an email to an email address, it is delivered to its recipient by a SMTP Server.
What is ISP?
ISP stands for Internet Service Provider. They are the companies who provide you service in terms of internet connection to connect to the internet.You will buy space on a Web Server from any Internet Service Provider. This space will be used to host your Website.
What is HTML?
HTML stands for Hyper Text Markup Language. This is the language in which we write web pages for any Website. Even the page you are reading right now is written in HTML.This is a subset of Standard Generalized Mark-Up Language (SGML) for electronic publishing, the specific standard used for the World Wide Web.
What is Hyperlink?
A hyperlink or simply a link is a selectable element in an electronic document that serves as an access point to other electronic resources. Typically, you click the hyperlink to access the linked resource. Familiar hyperlinks include buttons, icons, image maps, and clickable text links.
What is DNS?
DNS stands for Domain Name System. When someone types in your domain name, www.example.com, your browser will ask the Domain Name System to find the IP that hosts your site. When you register your domain name, your IP address should be put in a DNS along with your domain name. Without doing it your domain name will not be functioning properly.
What is W3C?
W3C stands for World Wide Web Consortium which is an international consortium of companies involved with the Internet and the Web.The W3C was founded in 1994 by Tim Berners-Lee, the original architect of the World Wide Web. The organization’s purpose is to develop open standards so that the Web evolves in a single direction rather than being splintered among competing factions. The W3C is the chief standards body for HTTP and HTML.
Explain working of internet protocols?
The internet and many other data networks work by organizing data into small pieces called packets. Each large data sent between two network devices is divided into smaller packets by the underlying hardware and software. Each network protocol defines the rules for how its data packets must be organized in specific ways according to the protocols the network supports.
What is an Internet protocol?
Internet Protocols are a set of rules that governs the communication and exchange of data over the internet. Both the sender and receiver should follow the same protocols in order to communicate the data. In order to understand it better, let’s take an example of a language. Any language has its own set of vocabulary and grammar which we need to know if we want to communicate in that language. Similarly, over the internet whenever we access a website or exchange some data with another device then these processes are governed by a set of rules called the internet protocols.
Why do we need protocols?
It may be that the sender and receiver of data are parts of different networks, located in different parts of the world having different data transfer rates. So, we need protocols to manage the flow control of data, access control of the link being shared in the communication channel. Suppose there is a sender X who has a data transmission rate of 10 Mbps. And, there is a receiver Y who has a data receiving rate of 5Mbps. Since the rate of receiving the data is slow so some data will be lost during transmission. In order to avoid this, the receiver Y needs to inform sender X about the speed mismatch so that the sender X can adjust its transmission rate. Similarly, the access control decides the node which will access the link shared in the communication channel at a particular instant of time. If not the transmitted data will collide if many computers send data simultaneously through the same link resulting in the corruption or loss of data.
Explain TCP/IP(Transmission Control Protocol/ Internet Protocol)
These are a set of standard rules that allows different types of computers to communicate with each other. The IP protocol ensures that each computer that is connected to the Internet is having a specific serial number called the IP address. TCP specifies how data is exchanged over the internet and how it should be broken into IP packets. It also makes sure that the packets have the information about the source of the message data, the destination of the message data, the sequence in which the message data should be re-assembled, and checks if the message has been sent correctly to the specific destination.The functionality of TCP/IP is divided into 4 layers with each one having specific protocols:Application Layer: The application layer makes sure that the data from the sending end is received in a format that is acceptable and supported at the receiving end.Transport Layer: The transport layer is responsible for the smooth transmission of data from one end to the other. It is also responsible for reliable connectivity, error recovery, and flow control of the data.Internet Layer: This Internet Layer moves packets from source to destination by connecting independent networks.Network Access Layer: The Network Access Layer sees how a computer connects to a network.
What is SMTP(Simple Mail Transfer Protocol)
These protocols are important for sending and distributing outgoing emails. This protocol uses the header of the mail to get the email id of the receiver and enters the mail into the queue of outgoing mails. And as soon as, it delivers the mail to the receiving email id, it removes the email from the outgoing list.
What is PPP(Point to Point Protocol)
It is a communication protocol that is used to create a direct connection between two communicating devices. This protocol defines the rules using which two devices will authenticate with each other and exchange information with each other. For example, A user connects his PC to the server of an Internet Service Provider also uses PPP. Similarly, for connecting two routers for direct communication it uses PPP.
What is FTP
This protocol is used for transferring files from one system to the other. This works on a client-server model. When a machine requests for file transfer from another machine, the FTO sets up a connection between the two and authenticates each other using their ID and Password. And, the desired file transfer takes place between the machines.
What is SFTP(Secure File Transfer Protocol)
SFTP which is also known as SSH FTP refers to File Transfer Protocol (FTP) over Secure Shell (SSH) as it encrypts both commands and data while in transmission. SFTP acts as an extension to SSH and encrypts files and data then sends them over a secure shell data stream. This protocol is used to remotely connect to other systems while executing commands from the command line.
What is HTTPS(HyperText Transfer Protocol Secure)
HTTPS is an extension of the Hypertext Transfer Protocol (HTTP). It is used for secure communication over a computer network with the SSL/TLS protocol for encryption and authentication. So, generally, a website has an HTTP protocol but if the website is such that it receives some sensitive information such as credit card details, debit card details, OTP, etc then it requires an SSL certificate installed to make the website more secure. So, before entering any sensitive information on a website, we should check if the link is HTTPS or not. If it is not HTTPS then it may not be secure enough to enter sensitive information.
