Who is your ideal client or customer? Are they male? Female? Teenaged? Middle-Aged? Dog-lovers? iPhone-users? Soccer players? Board game enthusiasts?
Targeting your key demographics has become infinitely easier since the rise of social media.
When you promote your business on TV or radio, targeting your key demographics is one of the first steps in developing your marketing agenda. If you're a liquor company, you don't put a commercial on ABC Family. If you're a toy company, you don't put a commercial on NPR. Television and radio allow you the opportunity to choose outlets based upon general demographics (a certain city, a broad age range, a majority gender, a certain time slot, etc.).
This is great - you don't have to advertise to everyone. These mediums let you choose a few broad parameters to broadcast within so that you don't waste your money advertising to people who won't be interested in your product or service anyway.
Imagine, though, if you could create an advertisement or campaign where you could define your target demographic so narrowly that you're only broadcasting to your ideal customer or client.
Social networks let you do this. Facebook users have already published every important piece of information you need to target your ideal customers. Twitter users show you exactly what they're interested in based upon who they follow and what they tweet.
If you're a sports bar, create a Facebook ad that is only displayed to men ages 21-55 whose Facebook activities include sports and bars and who live in your area.
If you're a pet store, only follow local Twitter users who talk about their pets or follow other pet-related users.
If you're a toy store, only advertise to users whose Facebook profiles say they have children, are children, or just love toys.
You get the point.
If you know your target demographics, social media makes it easy to pinpoint your future customers and broadcast your message to them. Social networks do the work for you.