According the CIPC in South Africa, a trade mark distinguishes you from other people in the

http://www.cipc.co.za/index.php/faqs/trade/

same line of work, and gives you an identity in the market place. Goods are things that can be manufactured, such as a radios, clothing, medicine, cosmetics, jewelry and cars. Goods can also be perishables, such as plants, meat, milk, fruits, and vegetables. A service is work done by a person or a group of people for other people. Some examples are a restaurant, a construction company and a food delivery service.

Although registration of a trade mark is not compulsory, and an unregistered trade mark does provide some protection under the common law, it is most advisable to apply for registration, because registration provides an effective basis for stopping infringement and others from appropriating and registering your trade mark.  Registration is also a guarantee of immunity to registered trade mark rights of any other party.  Use by the applicant of the trade mark prior to the application for registration, presents no bar to valid registration.  Such use can sometimes strengthen the position of a trade mark.

A trade mark is registered in one or more classes into which the goods and/or services fall.  In principle, a trade mark registration only protects the owner of a trade mark and prevents use of same or similar trade marks in the class in which a trade mark has been registered, although there is some protection against registration by a third party in classes similar to the goods or services in which trade marks have been registered.  A trade mark must be registered for goods or services falling in a particular class in accordance with the prescribed classification, e.g. class 25 for clothing, footwear and headgear, class 5 for pharmaceuticals and class 42 for the Internet services. The classification is an international one used in all countries and can be found on the CIPC website under “Trade Mark classification of goods and services”  http://www.cipc.co.za/index.php/trade-marks-patents-designs-copyright/trade-marks/ho/classification-goods-and-services .

A trade mark, once registered, is valid indefinitely but must be renewed every 10 years otherwise it will expire.  Some trade marks have been in existence and renewed every 10 years for over 100 years and are still in-force and used today.