Which of the following is a key component of on-page SEO?

Meta descriptions are a key component of on-page SEO because they provide a summary of a webpage's content, which appears in search engine results below the page title. This summary is crucial for attracting clicks from users browsing search results because it helps them understand what to expect from the page before deciding to visit. A well-crafted meta description can improve the click-through rate (CTR), which signals to search engines that the content is relevant and valuable, potentially boosting the page's ranking.

On-page SEO encompasses various elements that are directly on the website, including title tags, headings, and content optimization, alongside meta descriptions. The other options mentioned—backlinks, social media shares, and domain authority—are associated with off-page SEO factors and external signals of authority and relevance rather than individual page optimization. Therefore, meta descriptions clearly stand out as a fundamental aspect of on-page SEO.