DA in SEO, or Domain Authority in Search Engine Optimization, refers to a metric developed by Moz that predicts how well a website will rank on search engine result pages (SERPs). It is a score on a scale of 1-100 that takes into account various factors such as the quality and quantity of backlinks, website content, and overall website authority. A higher DA score indicates a stronger and more authoritative website, which can lead to better search engine rankings and increased organic traffic. DA is an important factor to consider when optimizing a website for search engines and should be regularly monitored and improved upon to achieve optimal SEO results.