HTML Reference Guide
<STRIKE> ... </STRIKE> STRIKETHROUGH
These are Physical Style elements that indicate a sequence of characters that has a horizontal line striking through the middle. The HTML 2 specification had STRIKE as a proposed element which did not reach the final specification, but HTML 3 revised the syntax to S. The HTML 3.2 recommendation reverted to the earlier syntax, and HTML 4.0 now includes BOTH usages. Many browsers support one or the other, or even both.