WATO = When any Attribute Then this cmd Otherwise that cmd.
Kind of like making rules in RM, but you can specify any attribute (without making intermediate virtual devices, etc) and execute any command (without making custom commands).
It also has the ability to do math on inputs for the trigger, more than just >, <, =... Like the rising and falling triggers mentioned above.
I use RM for most of my things, but WATO scratches a couple of very specific itches for me that would be possible in RM - but with a lot more work/rules.