What is competition?

I hate when people say they have no competition because they do things differently than their competition. "Our home video delivery service has no competition, because no one else is delivery videos to your home! With Orangina!" Or, "They're not a competitor because they sell CPM advertising, and we sell CPC."

Oy. The definition of a competitor is not someone who does exactly the same thing as you.

Oops, I just set myself up to define what the definition of competition is, didn't I? But anyway, it's not that.

It's closer to anyone who's product/service's existence will potentially lessen the time/money spent on your product/service. But by that definition, a guy's girlfriend is competition for your football broadcast (to be as stereotypical as possible).

Although looking at everyone as competition isn't necessarily productive, it's more realistic than saying no one is.