In photography, mainly 3 skills used to develop a good photograph, combined together is called the exposure triangle. It is made out of aperture, shutter speed, and ISO.
Aperture is used to control the depth of field in your photo. By having low aperture, it allows you to take picture in shallow depth of field, and by raising aperture, it allows you to taking pictures with wider depth of field. This can be useful in photo takings, because you can choose to blur the back ground to focus on one object, or to have everything clear in details. Some side effects of this would be that when aperture is low, the camera will be able to consume more light, and may cause the photo to be over-exposed. When aperture is high, the camera will not consume light as much, and may cause the photo to be underexposed.
Another component, the shutter speed, is used to decide how long or how fast the camera is taking a photo, this is a technique useful in capturing actions or showing motion of an object. By having a short shutter speed, photographers can capture moments that are too fast to be seen, such as bubble popping, water drops, or a running person. By slowing the shutter speed, it allows photos like having a series of dance moves in a single picture, or a trail of light to be taken. Though same as aperture, this will also effect the amount of light taken my the camera. Long shutter speed will make the photo bright since it have more time to consume in light, and fast shutter speed could cause the photo to be too dark.
The last component, ISO, is used to adjust the brightness of the photo. By raising up the ISO, you can have photos that are bright even if it is taken in a dark room. Though there down sides to this technique, which is that it create grains in the photo, causing it to be unclear. So normally it is ideal to keep the ISO as low as possible.
As a photography, it is very important to adjust these 3 components to be able to get the photo that you expect. And to do this, the exposure triangle is used. It is used to help with the balance of the 3 components when adjusting. As said before, it is best to keep ISO low. So the key will be to understand how to change the rest of the components. When wanting to raise aperture in a place with normal lighting, you can extend the shutter speed to avoid underexposure. And the same vise versa. This is like rotating a triangle. When moving one point of an triangle, the rest also change places. And since the change ISO should be avoided, the movement of the triangle, instead of changing the ISO, should be considered by the lighting of the surroundings. When taking photos in a dark room, if an photographer want to have a clear bright photo, he or she should lower the aperture, and raise the shutter speed, to allow enough light to be captured. By balancing all 3 of these skills, photographers will be likely to achieve its goal on the best photos they want to take.