List of free screen capture software required for windows operating system

I am looking for free software to capture screen in real time. Is there any free software which comes without ad or time limited version? The software should be able to save the files on its own and it should not ask me every time to save or to name the capture for instant. Can I also record video using screen capture along with the sound? I will not use it for any other purpose other than personal so looking only for free versions but have to be reliable, fast and smart in saving, interface and other sharing options. Thank you for sharing.