REITs are corporations
that purchase and manage real estate
on behalf of shareholders.
The acronym is formed by taking the first letter of each word in the formal term - Real Estate Investment Trust.
Investors typically like REITs because they pay out a high percentage of their earnings as dividends and REITs recieve favorable federal tax treatment at the corporate level so they are often able to operate quite efficiently. Most REITs focus are particular niches of the real estate market, e.g. Shopping malls, apartment complexes, commercial office buildings, etc...