What's Available - Tents for Camping
Whilst there isn't actually an international standard for camping tents as such, most manufacturers classify their tents as being:
For use in Summer
Designed for use in warm, relatively calm conditions. These are usually lightweight with good ventilation. Whilst they may withstand light showers, this type of tent will probably not be suitable for heavy persistent rain or high winds.
For Three Seasons use
These are the most common in the UK and are designed for use in Spring/Summer/Autumn conditions. They will usually be strengthened by incorporating a 3 pole structure and include a full flysheet plus space for storage.
These are 3 season tents that can be 'upgraded' to deal with winter conditions - by the introduction of additional poles for stability and panels over windows to increase ventilation whilst reducing wind draught.
For Four Season/mountain use
These are tents designed to deal with the worst weather conditions - even snow - so are suitable for use in mountainous terrain. As such they will be strengthened with at least 4 poles and extra guy ropes for stability, incorporate snow valances plus generous amounts of room to store the additional kit needed in winter conditions.
Whilst deciding whether you need a Summer, a 3 Season or a 4 Season tent is probably the most important choice you'll make, there are some other factors you might also consider: the shape of the tent, what it's made from, other characteristics such as weight or colour.