Like poles of magnets repel each other. Unlike poles of magnets attract each other.

Magnetic materials are the materials which are attracted by a magnet. Cobalt, nickel, iron and steel are attracted by magnet and hence, they are magnetic in nature. Aluminium, copper and lead are non magnetic in nature.

A bar magnet consists of two poles which are always apart and never located at the middle. Poles of a bar magnet are always located at two extreme ends of the magnet.

Bar magnets point in the North-South direction when suspended freely. This is because the Earth itself behaves as a magnet which causes a freely suspended magnet (or magnetic needle) to point always in a particular direction: North and South.
Materials which are attracted by a magnet are called magnetic materials. Hence, rubber is not a magnetic material and steel is a magnetic material. The strength of a magnet is maximum at the ends.

The magnetic property of a compact disc may be damaged when a powerful magnet is kept near it. Plastic, glass and wood are non-magnetic substances, hence they cannot be magnetised or demagnetised.

Lodestone is a natural magnet and hence aligns in north-south direction when freely suspended. In the old days, sailors used to find directions by freely suspending a piece of a lodestone. It works similar to a magnetic compass pointing towards north and south direction.

Magnetic field is a region where a magnet exhibits its magnetic influence. Magnetic substances which are within the magnetic field of a magnet, get attracted to it. The picture below shows the  magnetic field of a magnet.

 

Magnetic monopoles do not exist in nature. Even if we cut a magnet into two small parts, the new poles will always appear in pairs as shown in the diagram. Hence we cannot separate north and south poles of a magnet.