At the moment I'm making a sour dough starter. I began it on Thursday. But instead of Wheat flour ....which I didnt have any of, so initially I used Rye flour. So far so good.
I will let it rest on the shelf for now with a damp cloth over it to stop any bugs or dust getting into it. Sour dough starter is made by absorbing wild yeasts and good bacteria which are yeast forming and exist naturally in the air.
Once made you use a 200g to make bread and feed the starter to keep it going, there are sour dough starters that have been around for decades and the owners just keep adding to them to keep them going. All sour dough starter is different, individual you might say, depending on the flour the water and the atmosphere.
During the week after I think it has fermented enough and fed it a couple more times I will make some bread. The trick is not to allow it to get too hot or too cold as then it will either go off or just die. You need to keep an eye on it, a bit like a gold fish!