South by Southwest (SXSW) is a set of film, interactive, and music festivals and conferences that take place early each year in mid-March in Austin, Texas, United States. It began in 1987, and has continued to grow in both scope and size every year. In 2011, the conference lasted for 10 days with SXSW Interactive lasting for 5 days, Music for 6 days, and Film running concurrently for 9 days.

South by Southwest is run by the company SXSW, Inc. which plans and executes conferences, trade shows, festivals, and other events. In addition to the three main South by Southwest festivals, the company runs three other conferences, two in Austin: SXSWedu, a conference on educational innovation, and SXSW Eco, an environmental conference; and one in Las Vegas: SXSW V2V, a conference focused on innovative startups.

The music event has grown from 700 registrants in 1987 to over 28,000 registrants. SXSW Film and SXSW Interactive events have grown every year, most recently bringing over 51,000 registrants to Austin every March.