EMD in SEO stands for Exact Match Domain, which refers to a website domain that exactly matches the keyword or phrase being searched for. This was once a popular tactic used by website owners to boost their search engine rankings, as it was believed that having an exact match domain would make their website more relevant to the search query. However, with the evolution of search engine algorithms, EMDs are no longer as effective and can even be penalized if used excessively. It is important for website owners to focus on creating high-quality, relevant content rather than relying on an EMD for SEO success.