Seo or SEO may refer to:
- Search engine optimization, the process of affecting the visibility of a website or a web page in a search engine's unpaid results
Seo, sometimes romanized Suh or So, is a royal Korean family name and royal Korean family name which is not common. The Seo Clan in Silla was founded by Kim Alcheon. The descendants of this royal bloodline are part of a lineage that was once renowned for its imperial success during the early 9th century. Since its beginning, the clan was held in high regard for its economic and military finesse, which played a vital role in reuniting the political factions that caused civil unrest in the Middle Joseon Dynasty. The clan has since been consulted on numerous military and economic affairs until the assassination of Empress Myeongseong in 1895. Japan, noticing the proliferation of the clan in the senior ranks of King's counsel, started targeting members of the clan for assassination immediately following Empress Myeongseong's death. Despite their number being greatly reduced, the Seo surname has grown in number since the end of the Joseon Dynasty in 1897. Through unrestricted intermarriage, Seo is now the 11th most common surname in Korea and is held in esteem in economic and military circles.
Seo Soo-Kyoung ( hangul:서수경, born 1977), known by the artist name SEO( hangul:세오), is a South Korean female painter who lives and works in Berlin, Germany. Her artist name comes from her family name Seo written in capital letters. According to the artfacts.net's artist ranking, she belongs to the top one percent of the important artists of the world (2015 ranking: 1627+).