Pre written software is that type of software which is developed on the basis of generic concept where as user written/custom application software is developed based on the requirement of the particular business, organization or user requirements.

Software is basically a program or series of programs written in code that tells the computer what to do. Most of the software that you visualize on your monitor often times asks the user for input in order to tell the computer what the user wants it to do. A lot of software runs in the "background" without the user having to input anything and usually without the user even knowing that it is there.

The user interface is software.

User purchase quality software when user go to market to purchase software.

Penny Bauersfeld has written:

'Software by design' -- subject(s): Computer software, Development, Macintosh (Computer), Programming, User-computer interaction