Because most scripting languages are designed to work on human-readable code, which has a high redundancy, compression can be very effective and as simple as replacing long names used to identify variables and functions with shorter versions and/or removing white-space.
This allows software distributors to stay within the constraints of their chosen distribution media (such as CD-ROM, DVD-ROM, or floppy disk), or to reduce the time and bandwidth customers require to access software distributed via the Internet.
Executable compression can be used to prevent direct disassembly, mask string literals and modify signatures.
Another disadvantage is that some utilities can no longer identify run-time library dependencies, as only the statically linked extractor stub is visible.
In an attempt to solve the problem of malware obfuscated with the help of runtime packers the IEEE Industry Connections Security Group has introduced a software taggant system.
Executable compression used to be more popular when computers were limited to the storage capacity of floppy disks, which were both slow and low capacity media, and small hard drives; it allowed the computer to store more software in the same amount of space, without the inconvenience of having to manually unpack an archive file every time the user wanted to use the software.
Only very sophisticated compression formats, which add to load time, keep an executable small enough to enter these competitions.