Counter, as the name implies, can be used to count.  This is of course an over simplification, so we will elaborate on the subject through a series of examples.  

E.g. Counter could be set up to provide numbering of new entities from 1, incrementing by one for each created product, such that the first product would have the number 1 and the subsequent product the number 2 and so forth.  

Counter could also be set up to name entities upon creation, overriding user names, so that Accounts could be named "Account 1", "Account 2" and so on.  This is done by supplying Counter with a little information, in this case the prefix Account. 

Furthermore, Counter can be given even more specifications, such as a postfix, an incrementer (or decrementer) that specifies if counter should simply increment by one or perhaps 10 or perhaps -2 depending on circumstances and the starting number. 

As you can see, the possibilities are virtually uncountable, except perhaps, if you use Counter.  Counter comes with documentation and yet is entirely free of charge.  Simply follow the link in the box to the right.