All of the EOS cameras have hot shoes, and there are several dedicated flash units by Canon and third parties that work with the camera metering system.
For creative purposes, it’s sometimes desirable to hold the flash away from the camera, perhaps illuminating the subject from one side. If you want to use a dedicated flash unit and preserve all of its functions, then you need the Canon Off Camera Shoe Cord 2. The coiled cord can extend to about 2 m.
Given its relatively light weight, it’s a good and useful item to carry in the camera bag at all times.