On Friday when I was teaching a One on One Photography Session my client wanted to know about panning. I haven’t done panning for a while,
Panning is where you photograph a moving object so that the moving object is in focus, but the background is out of focus. It is done a lot in motor car racing, motorbike racing and cycling. 
Panning is not hard, but it take a lot of practice, and not many people can just do it first time. My first attempts were terrible. It took me quite a while to really get the knack of it. I would stand outside my house and practice on the cars as they went past. Cars driving past are great to practice on.
To do panning you have to control your shutter speed. I would put my camera on shutter priority and pick my shutter speed. The trick to panning is to move at the same speed as the thing you are photographing, move your camera that is. Sounds easy, try it and see.
To get the blur in the background you need a slow shutter speed, I did this with a shutter speed of 1/25 of a second. I had my spot on the front of the tram and I moved with it. I kept my finger millimetres off the shutter button until I thought I was ready, then pressed to focus and just clicked.
If you are starting this, I would start with a faster shutter speed, around 1/150th of a second. If you can pan the image and get the object you want in focus, then try going down to 1/100 of a second, then when you can do that go down again, just keep going down until you can get the moving object in focus and a lovely blurred background.
Good luck.
