I've seen it referred to as 'sticky header' and I think @Schmotty has it right. As suggested, remember to set your body margin-top or padding-top equal to the height of the header. This will offset the body content so that it sits right below, but not behind, the header.
Sticky headers are much simpler than sticky footers because it's much easier to predict where your page begins as opposed to where it ends.
Well a sticky footer can be just that same way if you always fix it to the bottom of the browser. And javascript isn't needed unless you want the sticky to move with the page while its where it is supposed to be and then stick after is official position is scrolled out of view.
I hope you guys got what i meant it.
How to implement it? Please give me link to any guide if there is any.
set the property of position to fixed and top to 0
Make sure to add a margin to the top of the page so that content doesn't start behind the fixed content.
Yes that thing.
Is there any detailed guide to it?
Anyway, I found this out, might be what you're looking for. Or it might be more complex than what you're looking for.
http://www.noobcube.com/tutorials/html-css/fixed-header-footer-layout-a-beginners-guide-/
Also, I don't really know of any specific naming for "this". I guess fixed positioning divs?
Sticky headers are much simpler than sticky footers because it's much easier to predict where your page begins as opposed to where it ends.