Eight years ago, one of the world's most successful venture capitalists penned a letter in the Wall Street Journal explaining how every single industry was being taken over by tech-driven disruptors and warning that the only incumbents that would avoid disruption were those that were investing heavily in software. 

His point: software is eating the world. 

The letter now lives in investing lore, but its point remains relevant today -- software has officially taken over.

The four largest companies in the S&P 500 are all tech companies that lean heavily on software -- Microsoft (NASDAQ:MSFT), Apple (NASDAQ:AAPL), Amazon (NASDAQ:AMZN), and Facebook (NASDAQ:FB) -- and some of the greatest investments of the past couple years have been software companies. 

But software isn't done consuming, and a whole new class of companies are harnessing it to capture incredible growth and reward investors along the way. Today, we're live on our YouTube channel to explain how the software model has changed over the past decade and to share a couple top SaaS stocks investors should keep their eyes on.