Social media–sharing sites allow users to share a wide range of media types, but many features are present on all of them. This section will detail some of those features.
Figure 5-3. Consumers have posted thousands of pictures of Nike shoes to Flickr.
A tag is a word assigned to a piece of content that helps describe it (e.g., book, work, blog, social media). A single piece of media can be tagged with multiple words, and tags are used to search content that is not textual, such as videos and photos; for instance, Figure 5-3 shows examples of media tagged with Nike. Tags are nonhierarchical, meaning they are not organized into a parent-child tree structure, and they are created by users rather than being determined by the site owner. The first use of a tag "creates" the category that all content with that tag falls into.
Social media sites typically support one of two types of tags: space separated and comma separated. Space-separated tags are entered in a list with a space between the tags. In space-separated tags, you can't have a single tag with a space inside it; if you wanted a tag called "social media" you would write it as "socialmedia." Some sites allow spaces if you enclose the tag in quotes. Comma-separated tags are written as a list with commas between the tags, so you can use spaces inside the tags.
It's a good idea to err on the side of too many tags, rather ...