Lossy and Lossless Compression

Question 1

What is compression?

Answer 1

Compression is the process of reducing the file size of data (like images) so it loads faster and uses less storage.

Question 2

What is lossy compression?

Answer 2

Lossy compression removes some data permanently to make the file smaller.
Used for images where perfect quality isn’t needed.

Question 3

Give an example of a lossy file format.

Answer 3

JPEG (.jpg) – often used for website photos.
It makes images smaller but loses some quality.

Question 4

What is lossless compression?

Answer 4

Lossless compression reduces file size without losing any data or quality.
The original file can be perfectly restored.

Question 5

Give an example of a lossless file format.

Answer 5

PNG (.png) – good for graphics with sharp edges like logos or icons.
No quality is lost.

Question 6

Why is compression useful for website graphics?

Answer 6

• Faster loading times
• Less bandwidth usage
• Better performance on slow connections

Question 7

When should you use lossy compression?

Answer 7

For photos where small file size is more important than perfect quality.

Question 8

When should you use lossless compression?

Answer 8

For logos, icons, or images needing clear detail.