Strike is a formatting element used to define strikethrough text, strikethrough text means the text is deleted text and it is no longer readable.
<stirke>Content</strike>
Or
<tag><strike>Content</strike></tag>
You can apply strike element to any element and use any where within a HTML document.
Strike is a pair tag and output of strike element is horizontal line through text like you can see in above example.
Open notepad or any other text editor, follow the following points.
save file with name task.html or task.htm and then open it using any browser and see results.
Don't forget strike is non empty element which means it always comes in pair.