What is Business Incubator?

Legal Definition
A business incubator in business speak is a company that helps new and startup companies to develop by providing services such as management training or office space.

The National Business Incubation Association (NBIA) defines business incubators as a catalyst tool for either regional or national economic development. NBIA categorizes their members’ incubators by the following five incubator types: academic institutions (which are more common since they reside next to universities in order to encourage knowledge transfer from university's to the business incubator); non-profit development corporations; for-profit property development ventures; venture capital firms, and combination of the above.

Business incubators differ from research and technology parks in their dedication to startup and early-stage companies. Research and technology parks, on the other hand, tend to be large-scale projects that house everything from corporate, government or university labs to very small companies. Most research and technology parks do not offer business assistance services, which are the hallmark of a business incubation program. However, many research and technology parks house incubation programs.

Incubators also differ from the U.S. Small Business Administration's Small Business Development Centers (and similar business support programs) in that they serve only selected clients. SBDCs are required by law to offer general business assistance to any company that contacts them for help. In addition, SBDCs work with any small business at any stage of development, not only startup companies. Many business incubation programs partner with their local SBDC to create a "one-stop shop" for entrepreneurial support.

Within European Union countries there are different EU and state funded programs that offer support in form of consulting, mentoring, prototype creation and other services and co-funding for them. TecHub is one of examples for IT companies and ideas.
-- Wikipedia
Legal Definition
Programs designed to accelerate the successful development of entrepreneurial companies through an array of business support resources and services, developed and orchestrated by incubator management and offered both in the incubator and through its network of contacts.