Touch typing is the ability of typing using only your "muscular memory."
Touch typing, in general, increases your productivity not just because of the rise of speed but also because in general you can be more careful about what you're writing without distracting your eyes to sneak peak the keyboard and therefore you will reduce mistakes and sooner identify the ones you made.
You can say that you're touch typing if:
1. find keys fast. 2. (obviously) do not often look at the keyboard. 3. use (at least most of) all available hand fingers.
Keybr is a great website I've been using for more than a year; it has a terrific algorithm which identifies your weak keys and creates personalized lessons based on data and statistics.
It also has a beautify achieved dashboard where you can see your progress through time.