When a person or an entity operates a business under a name which is different than his/her/its registered name, the entity is considered to be "doing business as" that name. The owner of the business must file a notice with the appropriate county (i.e. County Clerk) or state agency (i.e. Secretary of State). Depending on the state/county, this notice is sometimes referred to as either a "fictitious name" statement, or "assumed name", or a DBA (Doing Business As). Regardless, it is basically the business owner's public pronouncement that the business is using this name. And when that name is not otherwise "officially" registered, this notice somewhat officially connects the name being used with the owner of the business.
For example, if you a company (XYZ, Inc.) is operating a website (ReallyCoolLaptops.com), it could file a DBA for that name. It?s "official" name for operations might then be "XYZ, Inc, doing business as ReallyCoolLaptops.com"
The main purpose for filing this notice is to enable consumers to discover the names of the business owner, which will be important if a consumer needs to sue the business. It also allows the business owner to conduct transactions in the business' name, such as opening bank accounts and obtaining a taxpayer identification number; and to bring lawsuits under the business' name for business-related debts. Filing a fictitious name statement or DBA does not in itself confer any trademark protection or ownership for the name. Additionally, if an entity is formed in one state and it is operating in another state, that other state may require it to file a Foreign Authority to make the entity and the name "official" in that state.