Internet marketing with AdWords is a lot like fishing. So is marketing in general, but Internet marketing especially, where Internet search traffic is like a torrential flowing river of traffic, big and wide. Internet marketing with AdWords amounts to dropping a fishing line into the Internet River of search traffic.
The current of the Internet River consists largely of search engine traffic and the content or nature of the river's current is defined by keywords. Countless keyword phrases identify their own particular part of the current, and some parts of the current are much larger than other parts, of course, depending on the particular keywords and how many people are searching for those keywords.
The Google, Yahoo, and MSN search engines account for the vast bulk of the river's current of Internet search traffic.
Running a Google AdWords ad is like dropping a fishing lure into the river of traffic. The keyword associated with the ad makes up the lure itself. The text of the ad is like the decoration of the lure - some look attractive, some don't, to the prospective fishes swimming in the current of that keyword. The fishes decide in a split second whether to bite at the lure and click it.
The landing page that the ad takes them to is like the taste of the lure - some taste good, some don't, to the prospective fishes swimming in the current of that keyword. If the lure's landing page taste is tasty enough and the fish is hungry enough, then the fish swallows the lure and whips out a credit card or pays with PayPal. The fish is hooked. Otherwise the fish spits out the lure and moves on, or maybe saves lure to check it out later.
Some keyword currents in the river are teeming with fish, and so they draw the attention of a lot of anglers all trying to drop their lures in that part of the river. Some keywords become so competitive that you can't even get your lure down into the water, without shelling out a lot of cash to make room for your lure.
Of course, there are many tricks to the trade, on how to get your AdWords lures into the water at minimum cost, how to make your AdWords lures more attractive and how to get them in front of the maximum number of prospective fishes, and how to make the lures' landing pages more tasty.
So if this interests you, learn all you can about AdWords marketing strategies. There's a lot to know. One good source I've found is at BeatingAdwords.com - two dudes named Kyle and Carson have compiled a helpful list AdWords strategies, tips, and tricks of the trade - check it out.
Good luck fishing in the Internet River and making money with AdWords!