As Mokubai stated in the comments. AutoHotkey and AutoIt are both great applications for automating Windows. AutoHotkey was derived from AutoIt, but they have become significantly different from each-other over the years. You can obtain the same results with both of them.
Use AutoHotkey if you want to setup hotkeys or string expansions. I.E. Press button or key combination to perform scripted action.
Use AutoIt if you for example want it to fully automate install processes.
(I personally would still use AutoHotkey for this, but that's just my preference.)
Both AutoHotkey and AutoIt are extensively documented and have very active scripting communities and you can find plenty of help on either of their forums.
Check out the AutoHotkey scripting showcase for a small taste of what it can do.
Also check out the AutoHotkey Scripts and Functions forum. https://autohotkey.com/boards/viewforum.php?f=6
AutoIt also has a forum dedicated to example scripts that is worth a look.