Writing a hook - your attention-getting introduction - starts by knowing the end of your piece.

Which may come as a surprise, since your hook is the first sentence or two to your article,  blog post, essay, marketing copy, short story,  letter,  web page, or nearly any other written work. You might also call it your "hook sentence."

Just as it is the hook that snags the fish, the hook sentence catches the reader's interest so that he keeps reading.