I want free software for screen recording. Which captures voice also. Can anyone suggest any software which is freely available on internet like camtasia.

http://www.hongkiat.com/blog/win-screen-recording-softwares/ mentions some...

If you're on a Mac, just use Quicktime.

and if you are on 7 then you should try BB flash express. It will save the video in avi and swf format.

You should try Jing software.

Here - http://www.techsmith.com/download/jing/

try fraps:) not sure about voice recording though