xkcd explainer is a free Chrome add-on developed by Avadonia314. This browser extension provides detailed explanations for xkcd comics, making it easier for users to understand the content and references within each comic. The add-on displays the explanations below the comic image for convenient access.

The explanations are sourced from the explain xkcd wiki and are parsed into HTML format by the extension. Users can expect to find various formatting elements such as headings, subheadings, bold and italic text, bullet points, sub-bullet points, internal and external links, quotes, citation needed links, tables, TV Tropes links, and references/footnotes.

It's important to note that since the explanations are contributed by individuals, recently uploaded comics may not have explanations available immediately. Additionally, some explanations may be incomplete and are continually updated. Users who are interested in contributing to the community and enhancing the experience for other xkcd viewers can visit the explainxkcd.com wiki.