How are the exact versions of software determined?

Question

When you look at software they show the version. 3.46, 0.98, 6.39, etc. How is that number determined?

Answer 1

Kasey is almost correct....a 1.0 to 2.0 has to offer significantly more new functionality.  The numbering is determined by the legal department, not programming.  (retired IBM Exec Mgr)

Answer 2

By the programmer.

In general, a complete rewrite is like 1.0 to 2.0 change, a major revision is like 1.0 to 1.1, and minor change is 1.0.0 to 1.0.1.

Pre-release software gets a 0.xx number. Once it is released, it gets a 1.0 number, and patches add on from there.

Some companies prefer to use "release number" or "release date" instead.  

Answer 3

The number is set by the programmer when they release the software. Each company uses it's own method for numbering. Higher numbers imply later releases. The number is not automatically generated but specifically set by the programmer.