MORE EVENTS ON THIS DAY

Today: Today is Valentine's Day, the feast day of St. Valentine, a priest and physician who was martyred about 270 ce in Rome, and the tradition of exchanging greetings of love on Valentine's Day is based on the legend that Valentine had signed a letter to his jailer's daughter, with whom he had fallen in love, “from your Valentine.” [Why do we give Valentine's Day cards?]

2018: Amid scandals and corruption allegations, South AfricanPresident Jacob Zuma resigned and was later replaced by Cyril Ramaphosa. [Take our African leaders quiz.]

2005: Steve Chen, Chad Hurley, and Jawed Karim registered YouTube, a Web site for sharing videos; it would become hugely popular, with more than one billion unique users visiting the site every month. [ Test your knowledge of tech companies.]

1991: The psychological thriller The Silence of the Lambs was released in American theatres; widely regarded as a classic, it won five Academy Awards, including best picture, actor ( Anthony Hopkins), actress (Jodie Foster), and director ( Jonathan Demme). [How much do you know about scary movies?]

1946: American dancer, choreographer, and actor Gregory Hines, a major figure in the revitalization of tap dancing in the late 20th century, was born. [Test your knowledge of dance.]

1946: The first general-purpose high-speed electronic digital computer, the ENIAC (Electronic Numerical Integrator and Computer), was demonstrated to the public by its creators, J. Presper Eckert, Jr., and John W. Mauchly. [Discover how well you know computers and operating systems.]