What is the difference between char and varchar data types? Does it matter which one I use? Is there a benefit to using one over the other?

Thanks in advance.

Ok, did my homework...
If the text data in a column varies greatly in length, use a VARCHAR data type instead of a CHAR data type. Although the VARCHAR data type has slightly more overhead than the CHAR data type, the amount of space saved by using VARCHAR over CHAR on variable length columns can greatly reduce I/O reads, improving overall SQL Server performance. [6.5, 7.0, 2000]


Thanks