A trade mark is a particular word, phrase, single character, shape, picture, sound, smell, type of packaging or a combination of these elements that is used to identify and distinguish a particular product or service and distinguish it from competing products and services. Once a trade mark is registered, no other person can use it. For example, no-one can use a business name that infringes a registered trade mark, so it is wise to do a search of registered trade marks before choosing any particular business name. Searches can be done online at the IP Australia website.
Business names are not in themselves trade marks, unless they are registered as such.