1.2.5

• Data compression is when we make files smaller, while trying to make the compressed file as true to the original as possible
• Compressing files has many uses:

  • Smaller files take up less storage space on a device
  • Streaming and downloading files from the internet is quicker as they take up less bandwidth
  • It allows web pages to load more quickly in web browsers
  • Email services normally have restrictions on the size of attachment you can send- compressing the file allows you to send the same content with a much smaller file size
• Lossy compression works by permanently removing data from the file- this limits the number of bits the file needs and so reduces it size
• Lossless compression uses an algorithm that identifies repeated data and leaves it out, instead notes how many times the data is repeated in order to reinstate that data when uncompressed
• Advantages of lossy compression:

  • Greatly reduced file size, meaning more files can be stored
  • Lossy files take up less bandwidth so can be downloaded and streamed more quickly
  • Commonly used- lots of software can read lossy files
• Disadvantages of lossy compression:

  • Loses data- the file can't be turned back into the original
  • Can't be used on text or software files as these files need to retain all the information of the original
  • Worse quality than the original. But, this loss in quality is normally unnoticeable
• Advantages of lossless compression:

  • Data is only removed temporarily so there is no reduction in quality- the compressed file should look or sound like the original
  • Can be decompressed- turned back into the original
  • Can be used on text and software files
• Disadvantages of lossless compression:

  • Only a slight reduction in file size, so still take up quite a bit of space