You know how on newspaper comic strips, you can usually find a copyright notice in the gutters between two of the panels? The syndicates put that in place before they send the art file off to all the newspapers so there’s no legal question about who owns the copyright on the strip, regardless of what paper it appears in or when it starts appearing. Generally, it has nothing to do with the contents of the strip, and readers have learned to largely ignore it, but it’s still part and parcel of the comic.
That’s an example of what you might call “metadata.” It’s data that gives information about other data. The latter being the contents of the comic itself, and the former the legal notification about the contents. Most strips have at least two other pieces of metadata embedded in the strip itself as well: the creator’s name/signature and the date. These are, again, pieces of information about the strip but aren’t actually part of the strip itself. Some creators also include their website or perhaps an email address or Twitter handle as well.
With webcomics, there are inherently any number of pieces of metadata about a given comic strip. There will be a file size, for example, and both creation and modification dates. These, and a number of other similar data points, are created automatically by the computer. In some cases, the original creator is attributed, and even the software they used to create it. And while they’re attached to the art files themselves, most people never see them. The only reason they’re visible on newspaper comics is because that’s an analog format that doesn’t allow for metadata to be attached to, but invisible from, the main content.
The problem, however, is that since that metadata is invisible on webcomics, that means it’s easy to share around without any credit going back to the creator. A simple “Save As” procedure can overwrite a lot of the original metadata. (Note that when you save an image off the internet, the file creation date is when you saved the image, not when it was created by the original author.)
To combat this, one of the simplest and easiest thins a creator can do is fall back to what newspaper strip creators did and embed some of the basic information in the graphic itself. It can be run between the gutters, or simply off to the side of the comic, whatever makes the most sense given that particular comic’s format. But including the creator’s name and a copyright notice can mitigate many issues.
Sure, someone can unscrupulously go in with Photoshop and erase the name if they really wanted, but so too could they take a newspaper strip and slap some Wite-Out over the same information in a newspaper strip before photocopying it. Most people aren’t going to be so deliberate in their attempts to remove credit from a comic; most people just want to share it with their friends. By including basic credit and copyright information, a creator can more readily direct people back to their comic and, hopefully, continue to grow their audience!