First things first, what is metadata?
Metadata is information inside of your photographs, this includes the camera make, model, lens your camera settings and much more information, this is automatically added to your image by your camera. Here is an example of the metadata inside one of my recent images.

How do I view metadata?
On Mac
1) Open your image in preview.
2) Press the Tools tab, at the top of the screen.
3) Press show inspector.
On PC
1) Open the folder the image is located in
2) Right click on the image
3) Press properties
4) Press the details tab
In Photoshop
1) Open your image in Photoshop
2) Press the file tab, at the top left of the screen.
3) Press File Info
4) Press Camera Data
Tip: For a shortcut on Mac press 'command, option,shift and I'