If you're going camping then a 2 and 4 man tent is what you need to keep you safe and warm at night. A 2 and 4 man tent are the two standard sizes most commonly in use today, these are generally easy to pitch and easy to take down and fold away for storage. A 2 man tent is great for things like music festivals, traveling and for couples, a 2 man tent has the advantage of being lightweight and therefore easy to carry around and they don't take up much of a footprint.
A 4 man tent, being twice the size, is better for families or for groups of friends, a 4 man tent is probably the most versatile and there are many different kind to choose from on the market. Both 2 man tents and 4 man tents are made using either a single skin or double skin design, a single skin only has a single piece of weather-proof fabric whereas a double skin has an external flysheet to keep the rain off and an inner tent to comprise the living area.