It's very easy to get caught up in the Android versus iPhone duel and Google's recruiting battles with its newly-public Silicon Valley neighbor, Facebook.

But neither one of those companies worry Google executives as much as another that is actively taking money out of their pockets.

This company is from Washington, but no, it's not Microsoft.

Google's real rival, and real competition to watch over the next few years is Amazon.

Google is a search company, but the searches that it actually makes money from are the searches people do before they are about to buy something online. These commercial searches make up about 20 percent of total Google searches. Those searches are where the ads are.

What Googlers worry about in private is a growing trend among consumers to skip Google altogether, and to just go ahead and search for the product they would like to buy on Amazon.com, or, on mobile in an Amazon app.

There's data to prove this trend is real. According to ComScore, Amazon search queries are up 73 percent in the last year. But it makes intuitive sense doesn't it?

Why go through these steps …

Google search "rubber galoshes,"

Analyze some text links,

Click on one to go to a product page on some e-commerce store,

Click to add the item to your cart,

Input your credit card,

Input your address,

… when you can just …

Search amazon for "rubber galoshes,"

Click one button to buy the product with your usual credit card and have it shipped to your normal address.

On mobile, where Amazon has its own app and Google is just a search bar for a smaller-screened browser, the equation tips further in Amazon's balance.

The scenario gets even scarier for Google if Kindle phones and Kindle tablets gain ubiquity.

If you have a Kindle phone, which comes with free movies and books because you have an Amazon Prime account, which also gives you free shipping, why in the WORLD would you ever search to buy something through anything but Amazon?

You wouldn't.

That's why Amazon is practically giving its hardware away.

It's also why Amazon scares Google more than anything Facebook or Apple are up to.

And find out why Amazon has Google shaking in its boots below: