In order to use Google Handwriting Input, you just have to set the app as your default keyboard. From that moment on, every time you go to write something, instead of the regular keyboard, you'll see a space for drawing. You can either write one letter at a time (slower) or write word by word.
Google Handwriting Input is an interesting writing accessory because it lets you write in a more intuitive way on your Android device. Best of all, the app also recognizes 'emojis,' so you can try to draw any of the most famous 'emojis' and see what result you get.
Android 4.0.3 or higher required