I love hooks.

As a writer, I work hard on my hooks. When I was a magazine editor, the hook was often the best way for a writer to make a good first impression on me. And now, for me as a literary agent, the hook is the first and one of the most important criteria I use in evaluating a book pitch, proposal, or manuscript. A good book hook will often prompt me to give a project a more careful, hopeful look.

But some people really struggle with hooks. Some don’t even fully understand what a hook is. And that’s often not their fault, as hook is a fairly flexible term in the writing and publishing world. Editors, agents, and writers often use it to refer to several similar but different things.

Briefly, hook can mean:

• The overall unique appeal of an article or book
• The short, punchy summary of a book idea in a query or book proposal
• The first page, paragraph, or sentence of an article, story, or book

So, to illustrate the first definition: You meet a big, fancy, famous editor at a baseball game; and when she finds out you’re working on a book manuscript, she asks, “What’s your hook?” You say, “It’s an Amish romance in which the male protagonist is a zombie.” That’s a hook. It may not be a good one, but it’s a hook.

In the second case, it’s usually only a few sentences (or even a few words) that compellingly crystallize your book. I like it when the hook is at the very beginning of the proposal, and I also like it when it sounds like a movie trailer: “One woman. One man. Unforgiving wilderness.” Okay, so that may be a bit cliché; but you get the idea.

Finally, you read the third kind of hook all the time. For example, the first line of 1984: “It was a bright cold day in April, and the clocks were striking thirteen.” That’s a hook. Or the first paragraph of Annie Dillard’s The Writing Life: “When you write, you lay out a line of words. The line of words is a miner’s pick, a woodcarver’s gouge, a surgeon’s probe. You wield it, and it digs a path you follow. Is it a dead end, or have you located the real subject? You will know tomorrow, or this time next year.”

See? A hook is called a “hook” because it hooks the reader like a fish and reels him or her in. It captures interest and compels him or her to keep reading.

And, for writers who can deliver on the promise of the hook, it often leads to fame and fortune.