When I did a survey of my Mimi's Greenhouse customers asking what herb they would not want to be without, Basil was the number one choice.
It is useful fresh and is easy to dry and save for later. Who doesn't love fresh pesto! Basil is an annual but it will reseed freely if you let it go to seed in the fall. To keep it producing all those tasty leaves, keep the flowers deadheaded until the end of August and then let it go to seed.
There are several varieties of Basil: Large leaf (my favorite) Lemon Basil, Cinnamon Basil, Purple Basil, Spicy Globe Basil, just to name a few.
Search my blog (link on the side bar) to find more posts about growing and using Basil