How to Annotate a Book

Why annotating a book is worth the effort

Annotating turns reading from something that happens to you into something you do. When you have to decide what to underline and what to write beside it, you are forced to judge what matters, put ideas into your own words, and notice when you have lost the thread. Mortimer Adler made the case in his well-known 1941 essay “How to Mark a Book”: you only fully own a book, he argued, once you have written in it, because the marks record your thinking.

The second payoff comes later. A well-annotated book is one you can use again: when you write an essay, prepare for an exam or return years later, your marks show you in minutes where the key arguments, scenes and quotations are. An unmarked book, or one highlighted in yellow from cover to cover, has to be read again from the start.

Choose your tools: pencil, pen, tabs or a notebook

A pencil is the classic choice: it does not bleed through thin pages, and you can erase a note you later disagree with. A fine pen works on thicker paper. Highlighters are the weakest tool, because they invite marking without thinking and leave no room for words; if you use one, pair every highlight with a margin note.

For library books or anything you cannot write in, use small removable sticky notes or flags, and keep longer notes in a notebook with page numbers. On an e-reader or with a PDF, the built-in highlight and note tools do the same job, and many let you export your notes, which is worth doing at the end of each book. Whatever you use, have it within reach before you start; stopping to hunt for a pen breaks the habit.

A simple symbol system for annotating

A symbol key buys speed and consistency: a mark that always means the same thing can be read at a glance months later. Keep it short. Six or seven marks cover nearly everything, and writing the key inside the front cover keeps it at hand.

What to write in the margins

Symbols tell you where to look; words tell you why. The most useful margin notes are short and in your own words, and most fall into the four kinds listed below.

Annotate differently for different books. In a novel, track characters, recurring images and shifts in narration; in nonfiction, track the thesis, the evidence and the definitions; for a short passage you will write about, use the fuller method of close reading. In a textbook, turn headings into questions in the margin and answer them at the end, a habit at the center of studying a textbook well.

• Summary: three to six words naming what a paragraph does, such as “defines justice” or “first sign of guilt.”
• Question: what you want to know or doubt, such as “why does she trust him here?” or “evidence for this?”
• Reaction: agreement, disagreement or surprise, with a reason, such as “no: ignores cost” or “ironic, given ch. 3.”
• Connection: a link to another part of the book, another book, or your own experience.

How to annotate a book, chapter by chapter

Marking on the first pass makes most people mark too much. A read-then-mark rhythm, section by section, keeps annotation selective:

1. 1Before reading, look at the chapter title, headings and length, and write at the top of the first page one question you expect the chapter to answer.
2. 2Read a section or a few pages without marking anything, so you see the shape of the argument or scene first.
3. 3Go back over what you just read and annotate: a few underlines, symbols where they apply, and at least one margin note on any page worth marking.
4. 4Repeat section by section to the end of the chapter.
5. 5At the chapter's end, write a two- or three-sentence summary in the blank space or on a sticky note, from memory first, then check it.
6. 6Add entries to your index inside the back cover: a theme, character or key term, followed by page numbers.
7. 7Before your next session, reread your last summary instead of the last chapter.

What a well-annotated page looks like

Take the scene in Mary Shelley's Frankenstein where Victor sees his creature open its eyes for the first time. The page is famous, which makes it a good test: there is a lot you could mark, and the job is to mark only what you will need later. A useful annotation of that page might include these five marks:

Notice what is missing: no highlighted paragraphs and no plot copied into the margin. Five marks capture the chapter's turn, a key word to track, an open question, a connection and a summary, and those are exactly what you will need when you write about responsibility in the novel. Our guide to reading Frankenstein takes those questions further.

• A star beside the sentence where Victor's years of ambition turn to horror, the turning point of the chapter.
• A circle around “wretch,” Victor's word for the creature, with the note “his label: whose view are we getting?”
• A question mark beside his flight from the room, with “why run? who is responsible now?”
• A page reference back to his feverish description of the work itself, with “same eagerness, now reversed.”
• A chapter-end summary: “Victor succeeds, recoils, abandons the creature, falls ill.”

Turn your annotations into study material

Annotations pay off when you use them. Your question marks are a ready-made list of things to resolve before a class or exam. Your margin summaries, read in order, are an outline of the book. Your index lets you find every passage on a theme when you write an essay, turning a vague memory into specific evidence.

To remember what you read, turn your best annotations into questions and answer them without looking, the core of active recall. A starred passage becomes “what is the main claim of chapter 4, and what supports it?” If you also take notes on paper, the Cornell note-taking method gives chapter summaries and questions a clear layout.

Annotation mistakes to avoid

A few habits undo most of the benefit of annotating:

• Highlighting everything. If more than a sentence or two per page is marked, you are copying, not choosing.
• Marks with no words. A page of underlines tells you something mattered but not why.
• Complicated color codes. Five colors with five meanings slow you down and rarely survive past the first few chapters.
• Annotating only on the first read. A second pass, once you know where the chapter goes, produces better marks.
• Never looking back. Annotations you never revisit have done only half their job.