# About jekyll and github pages
**URL:** https://talk.jekyllrb.com/t/about-jekyll-and-github-pages/2237
**Category:** Help
**Created:** [October 9, 2018, 9:02pm UTC](https://talk.jekyllrb.com/t/about-jekyll-and-github-pages/2237 "2018-10-09T21:02:01Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@abhishek](https://talk.jekyllrb.com/u/abhishek)
#### Post date: [October 9, 2018, 9:02pm UTC](https://talk.jekyllrb.com/t/about-jekyll-and-github-pages/2237/1 "2018-10-09T21:02:01Z")
Actually i tried using theme cayman for github page and now when i was trying to build it using bundle exec jekyll build , it is throwing error of gem seo-tag.
**Liquid Exception: Liquid syntax error (line 6): Unknown tag ‘seo’ in /\_layouts/default.html**
Please help me.
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### Author:  [@mmistakes](https://talk.jekyllrb.com/u/mmistakes)
#### Post date: [October 11, 2018, 1:06pm UTC](https://talk.jekyllrb.com/t/about-jekyll-and-github-pages/2237/2 "2018-10-11T13:06:36Z")
I believe that theme uses the `{{ seo }}` tag, which requires a plugin to be installed.
If you’re not using the [GitHub Pages gem to build your site locally](https://help.github.com/articles/setting-up-your-github-pages-site-locally-with-jekyll/) then you’ll probably have to make sure it’s installed. Check their docs for those instructions.
> **[jekyll/jekyll-seo-tag](https://github.com/jekyll/jekyll-seo-tag)**
>
> A Jekyll plugin to add metadata tags for search engines and social networks to better index and display your site's content. - jekyll/jekyll-seo-tag