Tatiana Day (Russian: , Tatyanin den'), also known as Tatyana's Day or Students Day, is named after Saint Tatiana, a Christian martyr in 3rd-century Rome during the reign of Emperor Alexander Severus. It is also the name day for the name Tatiana. The Russian Orthodox Church celebrates St. Tatiana's feast on 12 January Julian, which corresponds to 25 January Gregorian in the 20th and 21st centuries. In Russia, the day is known as Students Day, commemorating the foundation of the Moscow State University.

Moscow State University (MSU; Russian: Московский государственный университет имени М. В. Ломоносова, often abbreviated МГУ, MGU) is a public research university located in Moscow, Russia. It was founded in 1755 by Mikhail Lomonosov. MSU was renamed Lomonosov University in 1940. Its current rector is Viktor Sadovnichiy.

Alumni of the university include leaders of the Soviet Union and other governments as well as a Patriarch of the Russian Orthodox Church. As of 2019, 13 Nobel laureates, six Fields Medal winners and one Turing Award winner have been affiliated with the university. According to the 2019 QS World University Rankings, it is the highest-ranking Russian educational institution, and according to the Nature Index, it is highest ranking Russian university for research output. The university includes 15 research institutes, 43 faculties, more than 300 departments and six branches (including five foreign ones - all in the Commonwealth of Independent States countries). Moscow State University is generally accepted as the leading higher educational institution in the former Soviet Union, retaining its legacy from the Soviet era.