I have made around 5 homebrews and have heard of yeast starters but have never used one. I have always used smack packs or dry yeast and just pitched that directly into the fermentation. They have all turned out fine, so now I am curious why I would use a yeast starter? Does it make for a better or faster brew? Do I only need it in certain situations? What other advantages could I be missing to using a yeast starter instead of not.
Plain and simple is that you don't NEED one if you just rehydrate the yeast and pitch you'll be fine.
The scenario where you would need to make a yeast starter is when brewing a high gravity beer and you are concerned that your yeast will not be as efficient as you would like, so you make a yeast starter to raise the cell count.