Relief Printing is a print process, with varying methods, that has been practiced for over a thousand years! A lot of the relief prints you probably see on a day-to-day basis are made from wood blocks or carved linoleum that then have ink applied and are pressed onto fabric or paper.
The process of relief printing in this way involves carving away at the surface of the block, creating recesses on the surface. The places that remain will be what prints onto the paper when you apply ink.
If you're interested in getting into relief printing for yourself, linoleum is perhaps the easiest material to start with as a carving material. When it comes to tools, Speedball often has a great starter package that is a fantastic deal (Check it out here). Honestly, just grab a piece of paper and you're ready to go with that kit. That little package makes relief printing, in my opinion, one of the most accessible crafts to get started with if you're looking for something new to try.
I personally love the upcycling aspect of block printing, because the same stamp can be used a hundred times adding new life to all kinds of everyday blank objects, boring canvas tote bag? BAM! Art! Random paper bag? BAM!! Art!
Some designs can be further decorated with paint or other materials. This pumpkin stamp I designed a few years ago, I was able to give a little more character with watercolors giving each other a distinct & unique personality.