There are four kinds of marketing situations, and the approach to each is radically different. Yet most of the time, we lump them together as just plain ‘marketing’.

If you are trying to sell a house or fill a job, you only need to persuade one person.

If you want to make your book sell a bunch of copies, your restaurant to be filled on Saturday night or your coaching practice to have a full schedule, you need to sell a few people.

On the other hand, viral bestsellers, killer websites and essential conferences hit their stride when most people in a marketplace have been converted. You can’t get elected President (most years, anyway) without persuading most of the people who vote.

Lastly, when the market is defined right, there are situation in which you need to persuade all of the people involved. If you need 51 Senators to agree with you on a bill, or if you need the purchasing committee at a big company to buy your software, then you need a unanimous decision.

This four-way distinction is important for two reasons. First, because you often have a choice. You can choose which approach your venture will take on its way to accomplishing its goals. Gandhi didn’t need most of the people to change India, he instead relied on a smaller few, but with more passion than most politicians are able to generate.

You could, for example, plan a business that works once almost everyone adopts it (like eBay) or you could alter the business so it works just fine if a much smaller universe of people embrace it (like threadless). Worth noting that neither business would work if just a few people showed up. 37Signals has done a great job of designing web products that only need to be sold to a few people, and then those people do the hard work of getting everyone in their organization to use them.

Here’s a quick list of how the four differ:

ONE: You’re a needle, the market is a haystack. Make your needle as sharp as you can, put it in as many haystacks as you can afford. Alternatively, you’ve already decided on your one (the date for the prom or the perfect job). In that case, throw the haystack out and engage in a custom, one-on-one patient effort to tell your story to the person who needs to hear it.

A FEW: Being exceptional matters most. Stand out, don’t fit in. Shun the non-believers.

MOST: Amplify the excitement of the few and make it easy for them to spread the story to the caring majority.

ALL: Compromise. You need to be many things to many people, embraced by the passionate but not offensive to the masses. Sooner or later, the issue for the reluctant part of the buyer community is that it becomes more expensive/risky to stand in the way of the group than it is to go along.

Blogs, for now, are almost always about the few. Google and Starbucks and the iPod are exciting stories because they’ve moved from the few to the most. The most important industry trade shows make huge profits because they’ve transitioned to the all.

Choose wisely, and realize that as you succeed, the game will change.