My canon? CR2 file appears in 7d?

Some low-level cameras only have JPG format, and good high-level cameras only have CR2 format, which saves a lot of original data. For example, even the black-and-white photos taken with the black-and-white function can be restored to color in the computer, which means that this format has a lot of room for post-processing in the computer, but it is not easy to display this format in the computer without special software (camera available or downloaded from official website), so the camera settings are saved in two formats at the same time, which is convenient to use. If you don't need or save memory card space in the future, you can only choose JPG format, otherwise you should set it to CR2(RAW) format or CR2+JPG format.

To add:

You have used such a good SLR camera as 7D. Of course, you must use CR2(RAW) format. I believe anyone who plays photography will tell you to use this format. RAW is much larger than JPG file. When downloading to computer, you need to use the attached software or card reader to download it, otherwise the file will be wrong.