Trademarks | Logo Trademarks | Domain Name Trademarks | Choosing Trademarks
You and your competitors can search for trademarks in the USPTO's trademark database.
If your trademark is a logo, the "literal elements" of the logo (e.g. the words "patent law" and "www.heels.com" in our old logo) are also entered into the database and are searchable. When you register a logo as a trademark, you are not claiming exclusive rights to the words in the logo (i.e. the literal elements of the logo) but are claiming rights to the graphical presentation of the logo as a whole.
Logos are not as strong from a legal perspective (since they protect just the particular logo, and if you change the logo, you'll need to file for a new trademark), but they are easier to register.
Since basic searches of the USPTO's trademark database return both word marks and literal elements from logo marks, both word marks and logos have deterrent effects (i.e. they discourage others from registering similar marks). So if you have a word mark that may be difficult to register because it is descriptive, then consider creating and registering a logo that includes the words.