How do people become an analyst?

A business analyst is more concerned with the basic business rules of the application. As such, they are usually more familiar with the day-to-day operations of whatever the application is used for. They also tend to work closely with the end users and may be the first point of contact with regards to gathering requirements for changes and new functionality. They are responsible for putting those requirements in more technical language and then passing them along to a systems analyst (who determines the actual changes and new programs required to fulfill them.) A BA will also often be involved in the testing (more typically system or acceptance testing rather than unit testing) of the changes.