As defined in CrossingTheChasm by GeoffreyMoore:

"A set of actual or potential customers for a given set of products or services who have a common set of needs or wants, and who reference each other when making a buying decision."
----
Given that MarketResearch is generally expensive, scattered  and hard to find it would be interesting to have a page such as this with projected info such as $M (that could be filled in and updated by WikiZens) to help identify MarketNiche s to help with business plans and career choices. A template could be (needs formatting):

  Country City Market Segment Category 2002 2003 2004 2005 2006 2007
  ------- ---- ------ ------- -------- ---- ---- ---- ---- ---- ----
  Afghanistan
  ...
  UK
  USA     NY City Programming Software Java
  ...
  Zimbabwe

''The market niche depend on the (needs for the) product or service you have in mind. Determining the needs of your intended customers is an essential part of planning a business. You can't just look these up in a directory, in my opinion - you have to do marketing (which doesn't necessarily require buying commercial market research). Marketing is an essential part of profitably delivering products and services that match your customer's needs and the capabilities of your organisation.''

''To take the example above - market niches are not necessarily defined geographically. I'll bet the Java programming software niche isn't restricted to NY, or indeed the US. They will reference each other through newsgroups, blogs, programming/development websites etc. My guess is they don't even have a common set of needs - the one man or small team customers will have different needs from, say, the development team at a large bank.'' -- PaulHudson

See also ThePointOfMarketing, EngineeringVsMarketing