A trademark is a word, name, symbol or design or any combination used, or intended to be used by an individual, business organization or legal entity to identify that the products and services with which the trademark appears originates from a unique source.

There are various kinds of trademark logos: combination (i.e. icon and text); logotype/word mark/letter mark (i.e. text or abbreviated text) and icon (symbol/brand mark).

In order to trademark logos it is required that a design search be performed. A trademark lawyer should evaluate this design search to make sure that your trademark logo does not contravene upon other trademark logos. Your trademark attorney can then recommend you on whether it is safe to continue with your plan to register the company logo as a trademark.
When you register a logo as a trademark, you are not claiming exclusive rights to the words or the literal elements present in the logo but are claiming rights to the graphical presentation of the logo as a whole. Word marks are stronger from a legal point of view but they are more difficult to register when they are vivid. Logos, in comparison, can’t be said to be strong trademarks from a legal perspective (since they look after a particular logo, and if one changes the logo, it is necessary to file for a new trademark), but they are easier to register. Both word marks and logos have deterrent effects as they discourage others from registering similar marks. So if you have a word mark that may be complicated to register, because it is descriptive, try creating logos that contain the words and then register the logo.

The trademark is usually represented by a (™) symbol, which confers some rights to it. Trademarks are not registered with the government trademarks office. Once they are registered, they become a registered mark denoted by a symbol (®).