I am new to using Arduino, and I have an Arduino Uno. For the projects I've done, I've only used the digital pins. 

I am building a small vehicle that uses stepper motors. I have run out of pins to control the motors for this vehicle. What are the analog pins for? Is it possible for me to use analog pins to control the rest of the step motors which I connect to the Arduino, or do I have to buy a bigger Arduino than Arduino Uno to control this contraption?