The third annual National Swing Day will take place January 17 with a series of social media takeovers celebrating some of the theatre industry's hardest-working actors, who must be prepared to go on with little notice for up to dozens of roles.

Started by Actors' Equity Association, National Swing Day honors the all-too-often unsung heroes of Broadway: swings. Look for the hashtag #EquityTeamSwing on all social channels for posts and discussions honoring this group of Broadway's most-versatile performers.

A swing is a member of a production's company that is essentially a general purpose ensemble understudy.

When a regularly performing member of the ensemble is going on in an understudy track or is otherwise out of a performance, it's up to a swing to fill in for the ensemble track. This means that a Broadway swing has to know and be ready to go on in anywhere from three to 20 or more separate ensemble roles, which is why many in the industry consider them among Broadway's hardest-working performers. They also have to have the vocal range, dance, and acting skills to be able to cover a wide variety of roles.

This year's festivities will include a @playbill Instagram Story takeover with SpongeBob SquarePants swing Alex Gibson beginning at 11 AM ET, an all-day @ActorsEquity Instagram takeover with swings currently on national tours of Hamilton, The Color Purple, On Your Feet!, and Bright Star; and a 5:30pm ET Facebook Live broadcast that will offer a behind the scenes look at life as a swing at A Bronx Tale.