Here's how Roku — the electronics company that's kept Apple and Amazon at bay — makes money

If you're familiar with Roku, the first thing that likely comes to mind are its digital media players. 
But the company has other ways of bringing in money that just by selling its $100 boxes and $40 streaming sticks. In fact, the fastest growing area of its business is actually selling advertising. 
The private company revealed some crucial details about its business on Friday when it publicly filed for an initial public offering of shares. The filing made with the Securities and