In some kind of photography, for instance landscape, you would want the entire picture to be in focus. To achieve the maximum depth of field at a given aperture, we need to pick a focus point somewhere between foreground and background which is called Hyper Focal Distance. When the lens is focused on the hyper focal distance, the depth of field extends from half the hyper focal distance to infinity. 
Now how do we calculate the hyper focal distance. There are few factors that determines the hyper focal distance. The size of the sensor, the focal length of the lens, and the f number and the distance of the subject from the camera. It’s a complicated calculation to understand therefore I would suggest you to download a mobile app which can give you the exact calculation. There are plenty of the apps available. Let’s try to understand one example. Suppose you are using a full frame camera with a 24 mm focal length lens. Aperture is f/8 and subject distance is 11 ft. Your hyper focal distance will be 8.284 ft. and the depth of field would range from 4.719 ft. to infinite. You would be wondering how this calculation arrived. Well, let’s focus on photography rather than these calculations and download some app or carry a hyper focal distance chart.
