There 2 sets of tools people use to aid them in programming. 1 is a framework and the other is a code library.
A framework such as Zend Freamwork is a collection of scripts or classes that interact with each other when needed to perform the tasks needed.
A code library on the other hand is a collection of scripts or classes that do not necessarily interact with each other and are simply used so that monotonous tasks do not have to be done all the time.
For example in a code library you may have several scripts such as a mailer, database connection layer class, xml parser etc. So when you came to do these tasks again instead of creating a new mailer you would simply use the mailer already created.
The concept is pretty much the same in any language you may ever code in. Creating your own code library can be a good idea.