A meta tag sits in the head section of an HTML document and passes page information to search engines and browsers. It is invisible on screen, yet it is a core signal that shapes SEO and social sharing experiences.
Key Meta Tags
| Tag | Role |
|---|---|
| title / description | Sets the search result title and summary |
| robots | Directs indexing and link crawling |
| viewport | Controls mobile responsive display |
| Open Graph / Twitter Card | Title and image for social shares |
| canonical | Specifies the preferred URL |
Title and description directly affect click-through rate, so they are covered separately in the Title & Description entry.
Index Control with the robots Meta
The robots meta directs whether a page is indexed and whether its links are crawled.
- index / noindex - Whether the page appears in search results
- follow / nofollow - Whether links on the page are crawled
Noindex removes duplicate or low-quality pages from search results. Note that pages blocked by the robots.txt file never have their robots meta read, so distinguish the roles of the two tools. This is fundamental to crawling and indexing management.
Social Sharing and Structured Signals
Open Graph and Twitter Card determine the preview shown when a link is shared. Missing images or titles cause a sharp drop in click-through rate.
Meta tags alone have limits in conveying rich meaning. To target rich results and AI citation share, apply structured data alongside them.
Notes
- The meta tag is a parent concept covering many HTML elements, including the meta tag.
- An incorrect noindex setting is a common cause of sudden traffic drops, so checking before deployment is essential.
- 238lab consults on meta and structured signal design that targets both search and generative engines at once.