Google Images is the second-largest search engine with about 20% share contribution for most sites, and YouTube is the third-largest search engine with about 3% share for most sites, according to
Tubics.com. Visual search encompasses the content and optimization of images and videos with a focus on gaining visibility in the image and video thumbnails that show up in the rich results of the SERPs. Milestone Research finds that image thumbnails appear in 20-25% of results with a similar proportion for video. That makes visual search an opportunity to gain visibility and traffic on almost 50% of searches.