png-8, png-24, jpeg, gif, svg.
But those are not above the interviewer wants final answer. Interviewers want to hear is Webp. (Is there a focus on new technologies, new things)
science about Webp: one kind WebP format, Google (google) designed to accelerate the development of image loading speed of image formats. JPEG picture compression volume is only about two-thirds, and can save a lot of server bandwidth and data space. Facebook Ebay and other famous sites have begun to test and use the WebP format.
In the case of the same mass, volume WebP image format JPEG images smaller than 40%
Just code porters