There are several forms of legal entity that can be used to run a merchant site.
Below, you will find a small study based on a sample of 14 online stores.
29% Limited Liability Company (LLC) (4 sites)
29% Sole Proprietorship (4 sites)
21% Public limited Company (INC. / Corporation) (3 sites)
14% other (2 sites)
7% Private Limited Company (LTD) (1 sites)