The exact number of websites that Google indexes is not known, but it is known that Google receives several million search queries each day, and the number of pages it sifts through to respond to those searches is in the trillions.
Yeah. And Google indexes and displays images in much the same way as it indexes websites. It’s easy to see that a non-search engine friendly image will get “lost” amid all of that. So, how can you make Google’s job easier?
Keep in mind that Google’s search engine spiders are essentially “robots” that can’t “see” images like you do. They can only “read” the text that is associated with any particular image.
Here’s an example of how complicated images can be: Think of the term “gas.”
You might have a photo that you have labeled “gas” and think that you have been pretty descriptive about what that image is. But, “gas” can refer to gasoline for a car. It can refer to oxygen. (Is “oxygen” referring to a tank of medical oxygen for a patient, or atmospheric gas?) It can refer to a gas burner on a stove. It can refer to natural gas. It can refer to natural gas of a different sort, as in belching or flatulence. See? Detail is crucial.
There is no way that Google’s search engines can tell what type of gas you mean, if “gas” is the only tag, or title, that you have given the photo.
Google search engines (and I’m using Google as a shorthand to refer to all major search engines, as they all function in relatively similar manners) look at the image’s filename, anchor text that points to it, and its “alt text.” I’ll explain more about what this is. If these textual cues are absent, then Google looks at the content on the page the image was found on to learn more about the image. Other important cues are also the page’s title. But, the tags that you put directly on the image are the most important.
To help make sure your images are indexed:
1. Make sure that the image filename is related to the image’s content: “gasoline” if it’s a gas pump; “oxygen” if it’s atmospheric gas, etc.
2. Enter something descriptive in the alt field that describes the visual components of the image in a human-friendly way. More about this…the “alt text” is what displays when the image can’t load for some reason. It is also what is spoken aloud by reader programs used by people with visual impairment when they search the web. Much like search engines, they can’t see the images, so they must rely on text. If your image is a gas pump, such as the one in this post, you might include “Driver filling fuel tank on a blue compact car from a gasoline pump at a gas station” in your alt text. If for some reason the image can’t load, such as if the user is connecting to the Internet via a slow dial up connection or they have images turned off, then “Driver filling fuel tank on a blue compact car from a gasoline pump at a gas station.” will appear in place of the image.
3. Try and place the image next to the content on the page that the image relates to.
5. Give your image a title. The title tag field is what displays when someone hovers a cursor over the image.