What is the meaning of %s, %1$s etc.?

From a Q&A Thread I’ve came to meet with some old things, but I’m afraid, I found myself in a condition that, I still don’t know the meaning of them and don’t know why to use them. %1$s – (found to load widget id) %2$s – (found to load widget class/classes) %s – (found here) … Read more