It is one of the factors that have an impact on your Focal Length as well as your Depth of field. It is affected by the size of your sensor and if you do not have a full frame camera, but you use an APS-C system, it will probably 1.5 smaller than the full-frame sensor. Because of that, your 35mm lens on a full frame camera and on APS-C camera will look different. Long story short, the bigger then sensor, the wider the angle of the view from the same focal length.