software programming, designing and engineering

Software is made by writing instructions, called a program in a computer language such as Java or Visual Basic. The program is translated into something that is understandable by a computer through a process calling compilation. Sometimes compiled programs are merged with other compiled programs or pieces of programs called libraries, through a process called linking. The compiled, linked program is fed into the computer one instruction at a time and the computer's microprocessor does what the instructions say. This is what happens when a program is run.

That is the low level answer of how software is made. At the high level, software is made by understanding what the computer needs to do for people - this is called requirements gathering, where many people are interviewed in an effort to determine what the computer must do to serve the need. Next, software designers describe and define the programs to accomplish what the computer must do, in a process called software architecture. Programmers write the programs and testers test it to make sure it does what it's supposed to do.