Advanced Photo System type C - APS-C dslr

APS-C sensor is exactly 1.6x smaller than FF, meaning it gets you 1.6x closer to your subject than with a FF camera, Phones and DSLR cameras both take pictures, but the size difference is enormous. Why is that? Because of the bigger sensor, which results in larger pixels and therefore better image quality, details and colors.

Confusing? Heres an easier explanation, with an actual example
Lets say you own 2 cameras, the Canon Rebel T6i and the Canon EOS 5D Mark III. The Rebel uses an APS-C sensor, whereas the 5D III uses a FF sensor.

You decide to use the Canon EF 50mm f/1.8 STM lens on both.
2. Because the Rebel T6i has a crop factor of 1.6x, any lens that you put on it will actually get you 1.6x closer to your subject than the same lens mounted on 5D Mark III. In our case, the 50mm would actually give you the same result as an 80mm lens on 5D III (50mm x 1.6 = 80mm) if shot from the same position

All Canon entry-level DSLR cameras and some semi-professional DSLRs use the APS-C sensor. The more professional ones use Full Frame (FF) sensors, which are even bigger. Whats the difference?
The 5D Mark III (Full Frame sensor) would capture the entire image you see above, whereas the Rebel T6i (APS-C sensor) would capture only whats inside the green box.
When we say the Rebel T6i has a 1.6x crop factor, it doesnt mean that the camera takes a picture and then for some reason decides to crop it, we just use these terms to explain this better.

Also, a 50mm lens is physically always a 50mm lens, regardless of what camera you mount it on. Its just the field of view compared to FF cameras that were talking about. Again, a 24-70mm lens on APS-C has a field of view equivalent to a 38-112mm lens (24mm x 1.6 = 38mm and 70mm x 1.6 = 112mm).

Crop Factor: 1.6x
Sensor Size: 22.2 x 14.8mm (Full Frame is 36 x 24mm)
How does this affect my images?

First, nothing happens to your images, theres no quality loss, no cropping or anything like that. The crop factor isnt something only DSLRs have, phones and cameras with smaller sensors have crop factors that are much bigger than 1.6x, some even up to 40x.

Is there anything bad about APS-C?
Since any lens you put on becomes 1.6x longer, this isnt really good if you want to capture as much as possible in your shot (landscape and indoor photography). To fix this, Canon created EF-S, a new lens mount back in 2003 specifically for APS-C cameras.

EF lens mount will work on APS-C and FF cameras
EF-S lens mount will work only on APS-C cameras
Since 2003, Canon has released a lot of EF-S lenses with the crop factor in mind, the majority of them being wide-angle. You can see the whole Canon lens list here or here.

However, the 1.6x crop factor is excellent for anyone who is into wildlife, animal, sport and portrait photography, as you can get closer to your subject without actually spending money on longer lenses. The Canon EF-S 55-250mm has the same field of view as an 88-400mm lens would on FF.

Nikon and a lot of other companies have crop factors around 1.6x as well, you can check them out here.
Canon APS-C Camera List:

Canon EOS 7D Mark II
Canon EOS 7D
Canon EOS 80D
Canon EOS 70D
Canon EOS 60D
Canon EOS 50D
Canon EOS 40D
Canon EOS 30D
Canon EOS 20D
Canon EOS 10D

Canon EOS 760D/Rebel T6s
Canon EOS 750D/Rebel T6i
Canon EOS 700D/Rebel T5i
Canon EOS 650D/Rebel T4i
Canon EOS 600D/Rebel T3i
Canon EOS 550D/Rebel T2i
Canon EOS 500D/Rebel T1i
Canon EOS 450D/Rebel XSi
Canon EOS 400D/Rebel XTi
Canon EOS 350D/Rebel XT
Canon EOS 300D/Rebel
Canon EOS 100D/Rebel SL1
Canon EOS 1300D/Rebel T6
Canon EOS 1200D/Rebel T5
Canon EOS 1100D/Rebel T3
Canon EOS 1000D/Rebel XS
Canon EOS D60
Canon EOS D30