Wide-angle lenses are one of the most popular types of lenses.
You can buy wide-angle lenses both as prime lenses and also as zoom lenses. It is common even for cheap disposable cameras to have fixed lenses with wide-angle capability.
Common focal lengths used for wide-angle lenses are 28mm and 35mm, and you can get lenses that can go from 17-35mm. Here is a 19-35mm wide-angle lens:
The 28mm lens produces a more extreme wide-angle effect than the 35mm lens.
With the 28mm lens you will certainly notice the wide-angle effect of the lens more, and you will need to be more careful not to introduce too much distortion as a result of this, unless you are intentionally trying to capture the distortion for artistic effect.
The shorter focal length has the effect of magnifying objects in the foreground and shrinking objects that are further away. This allows more, or at least larger, objects to be fitted into the frame than you would be able to with lenses with longer focal lengths. This is terribly useful for landscape and architectural photography, so you can fit more into your shot.
These lenses are also ideal for photographing small and confined spaces, such as building interiors. Real-estate agents use these lenses to photograph the entire room, and capture everything in it. Without a wide-angle lens, the only way to do this would be to step back and photograph from a distance, but this isn’t normally possible without moving the walls!
Due to the exaggerated depth effects that wide-angle lenses produce, mastering how to use this kind of lens can be a challenge. When using a wide-angle lens for the first time, the first thing to get used to is that the image encompasses a wider angle of the view. You will also notice a closer minimum focusing distance and you will be able to get much closer to the objects you are photographing.
Since objects near to you appear larger, this enables more detail to be captured in these up-front objects. And you are still able to capture the expanse of the background.
Here is a shot where the wide-angle lens has been used to exaggerate the linear perspective: