There are many ways to purchase an information System. You can get programmes that are ready made for home use like the Microsoft Office packages. Most Companies will look for something much more expansive to suit their everyday business needs.
This means the designing phase of the system is crucial to ensure all aspects are covered. The customer and the programme designer may have different opinions on what is needed for the succesful implementation of the programme into the business. Some of the problems that may occur can be corrected through very traditional methods like simply interviewing the customer. .This allows for an analysis of the current system and possible changes to be made. More modern techniques may be used like Joint Application Design. This gets a number of key people together to discuss what needs improving or needs to be introduced. This video explains it a bit better: http://www.youtube.com/watch?v=T-AhzjCTfQ0
Hope you enjoyed.