All customers have four essential characteristics:
They have a particular need.
People have all kinds of needs including basic survival needs (eg., food, shelter, health), rational needs (eg., dependability, durability, economy), and emotional needs (eg., love, sex appeal, status, security, acceptance, and power).
They have enough money to buy what you are selling.
Keep in mind that just because someone wants to own something you are selling does not mean they have enough money to buy it.
They have decision making power.
The key here is to spend your time wisely. Find the person who has the actual authority to make the choice of buying your product or service.
They need to have easy access to your product or service.
Accessibility is important. For example, if you wish to sell baked goods to people in your neighborhood, you must either take your goods directly to your customers or have a small shop where they can come to you.
Based on these characteristics, your job as a business owner is to answer the following four questions:
What need does my product or service satisfy?
Who needs and can afford what I am offering?
Who has the authority to say "yes" to the product or service I am offering?
How accessible is my product or service to my customers?
Your answers to these questions form the foundation what you need to learn form your marketing research efforts.
Once you know what you are looking for, you can find more about the specific characteristics of the customers you are targeting by looking at their interests, ages, heritage, income level, education, sex, family status, and occupations. These are often called the demographics of your customers.
Usually, demographics are limited to a certain geographical area. For example, if you are looking for information regarding potential customers in your neighborhood, you could research the demographics of your particular area code.
A good source of demographic information can be found online at the U.S. Census Bureau. If you have difficulty finding the information you are looking for online, you can contact any of the bureau's twelve regional offices for questions about your particular situation.