Link on how to start and maintain it : sourdough starter (homemade yeast)
I need to keep this one link for reference. I did start a sourdough starter last July but somehow because I travel so much, I kind of lost my starter. Now I am more determine to start again and to keep it alive.
Basically, a starter is unique. Each baker has its own in the kitchen, bubbling, alive and waiting to be mixed with ingredients to make wonderful breads. Back in my old days when I was living in the Yukon, I kept my starter above the fridge, on a mason jar, for about 3 years. Oh, how unique breads did I ever make in those days!