Indexes can help tremendously if you are using several tables where the data in them is linked. Your question really requires a lengthy explanation. Good db design always has an index or a key field in each table even if you surrently have only 1 table so that should the app grow you can build off that key field. Read up on db design for a good understanding.
Think of a book.<BR>If I asked you to find something in a book, and it didn't have an index, you would need to flip through the book until you found what you were looking for.<BR><BR>If it had an index, you could look up the word in the index, and know exactly which page to go to.<BR><BR>A database works pretty much like that (For the purpose of this question).<BR><BR>Damian