"Trademark" is the way the consuming public identifies the source of goods and services. It can be very precise like a logo, or it can be more amorphous like trade dressing, including color schemes, design and style (but not of clothing).
Registering a trademark for your business can put you in a very powerful position for the future if someone tries to imitate.
A federal registration search is a good first step, and I can make this affordable.
On the other side, if you are hit with a threatening "cease and desist" letter accusing you of stealing another business's trademark, you may need to defend yourself. Many marks are not exclusive (even if registered) and there is a grey area that may allow you to continue using it without fear, especially when the mark is widely utilized, or is arguably protected under 1st amendment freedom of expression.
The federal law that governs Trademark also embraces a wide area of commercial law including advertising, unfair business practices, and tarnishment of a brand.