There are three main areas in Intellectual Property Law. As you mentioned, they are patents, trademarks, and copyrights. These laws are meant to protect consumers, businesses, artists or inventors.
A patent is an official right that is used to protect the inventor of an original product or process. Once a person invents something, whether it be a machine, tool or process, that has a noticeable and original result, acquiring a patent can be very worthwhile. Once patented, an invention cannot be used by other parties , without explicit permission from the patent holder. If infringement occurs, and someone is illegally using a patented product or process, the patent holder has the right to seek compensation.
A trademark is designed to protect both businesses and consumers. A trademark is a distinctive mark, logo, or symbol that is used to identify a product. For example, the large M on McDonalds' signs is an example of a trademark. Because a customer associates a certain service or result with a symbol or marking, it would be unfair to let that mark be used in a different industry or manner. To protect a trademark is to protect the reputation of a business, while at the same time ensuring that a customer is able to relate that trademark with a certain type of product.
A copyright does not apply to concrete objects like inventions or businesses, but is used in the art industry. A copyright is the legal right of a composer, writer or exclusive owner of an artistic work to control how that work is used. Works that can be copyrighted include novels, music, video, computer software and fine arts. The work must be of a creative nature to be able to receive a copyright. Also a copyright cannot protect the ideas of an artist, only the expression of those ideas.