It’s easy to forget that Google is primarily an advertising company. Everything it does is about capturing more eyeballs for adverts and getting better at serving those ads to the right demographic. The company is very good at it too.

According to EMarketer estimates, Google is the undisputed lord and master of online advertising. We already knew it was topping the charts for Web-search ads and mobile ads, now we learn it is beating Facebook on display ads too. Display ads are basically bigger ads with graphical or even interactive elements and also video ads. Google has been selling them to millions of non-Google sites and also using YouTube to serve them up to the masses.

The EMarketer report suggests that has led to net display-ad revenue of $2.31 billion for Google, which is 15.4 percent of the total U.S. market. That compares to $2.16 billion for Facebook, which is 14.4 percent of the total U.S. market. That figure doesn’t take into account what Google pays to partner sites, its so-called “traffic acquisition costs” but it is still an impressive chunk of change.

Google has been fighting hard for this market. It outlaid over $4 billion to acquire companies like DoubleClick and to develop an easy-to-use platform for advertisers and publishers. Google is really aiming to be a one-stop-shop capable of covering everything a marketing campaign needs. It is gobbling up market share from Yahoo and AOL and more than holding its own against Facebook.

We heard the Facebook search rumor recently about the possibility of the social media giant attempting to get into the search engine business. That was probably just Zuckerberg trying and succeeding in getting a share price boost. What is certain, though, is that Facebook and Google will be going toe-to-toe in the advertising market for the foreseeable future and it could get nasty.