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1.5.2 Utility Software

Utility software performs housekeeping tasks, such as:

The J277 specification requires you to know about the last three of these.

Application software, often just called "apps", help the user to perform specific tasks, including:

Encryption utility software converts plaintext into cyphertext using a key, and back again.

This ensures messages can only be read by the intended recipient.

A full overview of the encryption process is covered in 1.3.2 Encryption

Data compression utility software reduces the size of files on a computer.

The benefits of reducing file size are:

A full overview of compression is covered in 1.2.5 Compression

When files are saved, they are broken into small blocks of data
When files get deleted, they leave empty blocks between other blocks of data
Blocks from new files fill up the little gaps, but may not be contiguous
Over time, data is scattered across the hard drive. The disk is said to be fragmented
The data is slower to access because the drive head must physically move to each block’s location, which may be quite far from the previous block

Defragmentation rearranges the data into contiguous blocks. This allows the disk's mechanism to move from the first to the last block in one action.

Solid state disks should not be defragmented. This is because:

SSDs have a limited number of read/write cycles. Defragmentation uses a significant number of cycles, so the device's lifespan is reduced
SSDs are extremely fast – fragmentation will not reduce access times.

You can use the defragmentation simulator to help you understand how the process works.