How do tiles and samples work when rendering?

Support Basics & Interface
1

Hi, i just had a general question. In the render options you have the option to change samples and tiles; what are these two things exactly and how do they work?

Thanks.

2

Greg Zaal presents an add-on that automates the selection of proper tile sizes for your renders.http://www.blendernation.com/2013/10/01/auto-tile-size-addon/

Tutorial http://www.blenderguru.com/4-easy-ways-to-speed-up-cycles/

3

Ok; thanks man.

4

I wanted to know how they “work.” Whats the difference if I render by x:16 y:16 or x:64 y:64?