Meta tags used for SEO (Search Engine Optimization) play a crucial role in providing information to search engines about the content and purpose of a webpage. While some meta tags have lost their significance over the years due to abuse and misuse, others remain essential for optimizing a webpage's visibility in search engine results. Here are some of the most important meta tags for SEO:

Title Tag: The title tag is one of the most critical meta tags for SEO. It defines the title of the webpage and appears as the clickable headline in search engine results. It's essential to include relevant keywords in the title tag, as it can significantly impact click-through rates and search engine ranking. The recommended length is around 50-60 characters.

Description Tag: The meta description tag provides a brief summary of the webpage's content. Though it doesn't directly affect rankings, a well-crafted meta description can entice users to click on your link in search results. It's recommended to write a compelling description that includes relevant keywords. Aim for a length of 150-160 characters and include relevant keywords.

Viewport Tag: The viewport meta tag is essential for ensuring that your webpage is mobile-friendly and responsive. This tag helps the browser understand how to scale and display the content correctly on various devices.

Canonical Tag: The canonical tag helps address duplicate content issues by specifying the preferred URL for a webpage when there are multiple URLs pointing to the same content. It consolidates the ranking signals for the specified URL.

Robots Tag: The robots meta tag instructs search engine crawlers on how to handle indexing and following links on the page. For example, you can use it to disallow search engines from indexing certain pages or directories.

Open Graph Meta Tags: While primarily used for social media sharing, Open Graph meta tags can indirectly impact SEO by controlling how your content appears when shared on social platforms. This can influence user engagement and click-through rates.

Remember that while optimizing meta tags is essential for SEO, providing valuable and relevant content to your audience remains the most critical factor in achieving high rankings and user engagement. Also, keep in mind that search engine algorithms frequently change, so it's important to stay updated with the latest SEO best practices.