Putting up the backer board for the new tile. In the old days they used plain old drywall, but, when a leak in the tile lets water thru the tile and into the drywall, it becomes wetwall and just dissolves. This job is being done with state-of-the-art Hardiebacker pure concrete board. It's so waterproof you can immerse it in water for 20 years without trouble.
Being pure concrete, how do you cut it? Two ways. Score it with a box cutter knife and snap it. Or cut it with a diamond blade in a skilsaw. Score and snap is the way to go for most cuts. For real thin cuts, you gotta use the saw. Seven inch diamond blade was cheaper than you might think, only $13 at the local Big Box. Use the skilsaw out of doors, it makes a dense cloud of cement saw dust that is nasty stuff to clean up. Bad for the lungs too. Holes for pipes get cut with an ordinary hole saw in an electric drill.