Not affected by changes in Capitalisation, ie upper case or lower case. Opposite of case-sensitive.

For instance, "EVERYTHING", "everything" and "Everything" are different in a case-sensitive comparison, but the same in a case-insensitive comparison.

In some programming languages, for instance C, the source code is case-sensitive. In some, for instance Pascal, it is not. Most programming languages will allow the programmer to compare strings in either case-sensitive or case-insensitive ways.

In some operating systems, e.g. UNIX, the file system is case-sensitive. In some operating systems, e.g. Windows, it is not. On some older OS's (e.g. pre-windows DOS) the point is moot as capitalisation is not stored at all.

e.g. Under unix, you can have two files in the same directory called 'fred' and 'FRED'. If you ask for the file called 'Fred', you will get neither of them, but a 'file not found' error. Some consider this to be a plus.