text: If you're using a fil that already has a name, when you choose "save" you'll save the new version ON that file, without prompting. Whenever you should "save as" you'll pick the location, name, file type, etc. of that file you're working on =)\nUndo means to go back to the last action you performed. \nFor example, you just asked this question and decided it was silly and changed it. Then you thought "Oh, I liked what I worte, and I'm curious... But I erased it! What can I do?", then you clic on Undo, and you'll have your question written again. But, once you're done, you think you'd be better if no one see this question. Just press Redo, and you'll erase it again.\nHope you understood! =D