1/2.3″ This is the standard image sensor size in GoPro cameras. 1/1.9″ New image size in Hero11 Black and Black Mini. 1/1.7″. 2/3″. CX (Nikon) APS-C. 35 mm (Full frame) This is the standard sensor size that all others are compared against. The crop factor (see above) is used to compare other sensors against this size.
(For comparison, a full-frame sensor is around 30 times the size of the 1/2.55" sensor in the iPhone 12.) The relative sizes of 35mm (pink), APS-C Nikon (red) and APS-C Canon (green). For DSLRs and mirrorless cameras , the most common crop sensor size is APS-C, which is around 24mm x 16mm.
The three major camera companies, Canon, Nikon, and Sony, carry both of these styles. A full-frame sensor captures an image in the size equal to that which was captured on 35mm film. As you might infer from its name, a crop sensor is smaller than a full sensor. It has been “cropped down” from the size of the larger, full sensor.