Market capitalization is a measure of what investors think a company is worth, so it basically represents size. In order to get a little perspective on the relative size of some of the companies with which we, as gamers, are most familiar, I have thrown together the below chart.
As with all thrown together financial charts it has its shortcomings. Private companies, such as Bioware, SNK Playmore and Treasure cannot be included since they are not required to reveal their size and there is no market to determine it. Also, (and this may come as a shock to some of you) several of these companies are Japanese. This means that in addition to their market cap changing day to day based on price changes, when expressed in US Dollars, they change with foreign exchange rates as well.
I have also included a few other relevant companies. Exxon Mobil is the largest company in the United States (probably the world, I was a bit too lazy to check). Starbucks and Pepsi provide the caffeine necessary to play video games all night. And PMC Sierra makes semiconductors and has the distinction of being the smallest company included in the Standard and Poors 500, a measure of some randomly selected stocks meant to represent the larger companies in the US market. Enjoy.