If you want to make the best out of your camera, the one thing that you need to know is ISO. This is the amount of sensitivity to light your camera is. A lower ISO number indicates that your camera is less sensitive to light. However, a higher ISO number means that your camera’s light sensitivity is high.
A sensor, found inside a camera, is what is responsible for changing the light sensitivity of your camera. It is very important because it is the one that gathers all the light that gets into the camera and transforms it into the image that you will get. If the sensitivity is high, the sensor captures images perfectly even in low light environments. You, therefore, do not need a flash if you have a high ISO. However, it is also important to understand that the higher the sensitivity, the more the grain or noise in the picture.
Base ISO
This is the lowest sensor’s ISO number in every camera. It is meant to produce the highest image quality of the camera without adding 
any noise to the picture. The Base ISO normally depends on the type of camera you purchase. It can be anything between 100 and 200. To get the best image quality, it is always advisable to stick with the Base ISO. However, this can be difficult to work with in low light environments and that is where you may need to increase (to the power of two) the ISO number.
When a sensor is more sensitive to light, it basically means that it can capture an image faster or with less time. For example, if the Base ISO of your camera is 100 and you adjust the ISO number to 700, it means that the sensor is seven times more sensitive to light. In simpler terms, it means that it needs seven times less time to capture the same image that it would have captured with base ISO 100.
Increasing ISO can make a huge difference when capturing moving objects. It is perfect for moving subjects. If the right ISO is not used, the resultant photo may be a blur. When light is enough, you should always stick to the lowest base ISO to get as much detail and also have the highest image quality.
Conclusion
To get expert shots, you need to understand the concept of ISO clearly. The better your understanding of ISO, the better your photos will be in turn.