A trademark can be a word, a graphic design, a picture, a color, a sound, a character, even a smell. Or a combination of any of them. It’s just like your own name. That’s how other people identify you.
The stronger the mark, the more likely it will be enforceable against others and the easier it will be to stop them from using the same or similar mark on the same or similar goods.
Doing a trademark search is not a pre-requisite to using or registering your mark.