The <track> element is used as a child of an <audio> or <video> element and adds a time-based data source to the parent media element. For example, the <track> element can be used to add timed subtitles to a video and closed captions to audio content.
The <tfoot> element identifies one or more <tr> elements as containing summary contents of a table's columns. The <tfoot> element must be the direct descendant of a <table> element. In HTML5, <tfoot> can be placed either before or after <tbody> and <tr> elements, but must appear after any <caption>, <colgroup>, and <thead> elements.
The <tbody> element must be a direct descendant of a <table> element and is used to identify <tr> elements that comprise the body of the table. The <tbody> element should always come after a <thead> element and may come before or after a <tfoot> element.