A notebook (also notepad, writing pad, drawing pad, legal pad, etc.) is a book, usually of paper, of which various uses can be made, including writing, drawing, and scrapbooking. Notebooks can be distinguished along several dimensions and sub-dimensions:
History

The codex, a binding of leaves of writing material (usually parchment or papyrus), was used in Classical Rome. It is not known whether it was bound before or after a scribe had written on the sheets, however, leaving unclear whether it was originally used as a notebook.

The legal pad is claimed to have been invented by the founder of the American Pad & Paper Company in 1888 and in 1920 by Australian J. A Birchall, who first assembled paper on a cardboard backing, rather than leaving it loose leaf.

More accurately, a legal pad may be considered a notebook, but a notebook may not always be considered a legal pad.
Binding and cover

Principal types of binding are padding, perfect, spiral, comb, sewn, clasp, disc, and pressure, some of which can be combined. Binding methods can affect whether a notebook can lie flat when open and whether the pages are likely to remain attached. The cover material is usually distinct from the writing surface material, more durable, more decorative, and more firmly attached. It also is stiffer than the leaves, even taken together. Cover materials should not contribute to damage or discomfort.

It is frequently cheaper to purchase notebooks that are spiral-bound, meaning that a spiral of wire is looped through large perforations at the top or side of the page. Other bound notebooks are available that use glue to hold the pages together; this process is commonly referred to as "padding". [1] Today it is common for pages in such notebooks to include a thin line of perforations that make it easier to tear out the page. Spiral-bound pages can be torn out but frequently leave thin scraggly strips from the small amount of paper that is within the spiral, as well as an uneven rip along the top of the torn-out page. Moleskine notebooks include a sewn spine that allows it to lie flat.

Variations of notebooks that allow pages to be added, removed, and replaced are bound by either rings, rods, or discs. In each of these systems the pages are modified with perforations that facilitate the specific binding mechanism's ability to secure them. Ring-bound and rod-bound notebooks secure their contents by threading perforated pages around straight or curved prongs. In the open position, the pages can be removed and re-arranged. In the closed position, the pages are kept in order. Disc-bound notebooks remove the open or closed operation by modifying the pages themselves. A page perforated for a disc-bound binding system contains a row of teeth along the side edge of the page that grip onto the outside raised perimeter of individual discs. Pages can be added or removed at any time by peeling the perforations away from each disc.
Uses

Artists often use large notebooks which include wide spaces of blank paper appropriate for drawing. Lawyers are also known for using rather large notebooks known as legal pads that contain lined paper (often yellow in color) and are appropriate for use on tables and desks. These horizontal lines or "rules" are sometimes classified according to their space apart with "wide rule" the farthest, "college rule" closer, "legal rule" slightly closer and "narrow rule" closest, allowing more lines of text per page. When sewn into a pasteboard backing, these may be called composition books, or in smaller signatures may be called "blue books" or exam books and used for essay exams. In contrast, journalists prefer small, hand-held notebooks for portability (often called reporters' notebooks), and sometimes use shorthand when taking notes. Scientists and other researchers use lab notebooks to document their experiments. The pages in lab notebooks are sometimes graph paper to make it easier to plot data. Police officers are required to write notes on what they observed whilst on duty, to do this they use a Police notebook.