What are you selling?

What you are selling has a huge impact on who you are selling to. Let's say you want to sell a Gizmo Widget - it is the most awesome Widget every created, but the Gizmo Widget is really only super awesome for people that know how to use it - typically people under the age of 45.

BOOM - you've just defined a portion of you target market.

Primary things to consider when defining your target market include: age, gender, ethnicity, location. Defining the demographics of a target market can even extend to more in-depth factors like religion, diet, income, home value, and marital status.