What is the RAW format of Canon 550D?

There is nothing wrong with the camera. RAW format is the original data format unique to cameras. When I bought the camera, there were software or plug-ins on the CD-ROM. Now there are many image reading softwares on the Internet that can read the RAW format. However, if you are not specialized in photography, you need to print super-large photos, and post-processing has high requirements. I suggest you use JPG format. In 550D, it can be set to L M S at will, and L effect is better. I wish you a happy photography!