Scraping Reading pages from a site with a program and keeping some of what is on them.

Crawling Following links from page to page the way a search engine does; scraping is what you keep.

Bot Any program that fetches pages without a person clicking.

User agent The name a program gives itself in every request; how a site tells you from a browser.

Rate limit A cap on requests per period; over it the site slows or refuses you.

WAF A firewall in front of a site that blocks requests it judges hostile, bots included.

CDN Servers around the world that serve a site near the visitor; the machine you reach is rarely the operator's.

Bot challenge A test in front of a page to decide whether you are a person; a court has called one a lock.

CAPTCHA A challenge a program is not meant to pass; a careful crawler stops at one.

Login wall Pages that show only after signing in; behind one you are inside the terms.

Terms of service The site's contract with its visitors, whether or not anyone read it.

Browsewrap Terms at a link nobody clicked; they bind only with notice.

Clickwrap Terms you agreed to by ticking a box or making an account; these bind.

Cease-and-desist letter A letter telling you to stop; going on breaks the terms and, in many places, is unauthorised access.

Text and data mining (TDM) opt-out A rightsholder's machine-readable no; in the EU it switches the mining exception off.

Text and data mining Letting a program read works at scale, including to train a model.

Fair use and fair dealing The US doctrine, and its narrower cousins elsewhere, that allow some copying without permission.

Database right A right in the work of compiling a database, in the EU and a few other places, whatever the copyright in its contents.

Technological protection measure A lock on a copyrighted work; defeating it is its own offence.

Authorized access The hinge of every computer-misuse statute, read differently in each.

Personal data Any information about an identifiable person, whether or not they published it.

Data subject The person the personal data is about.

Controller The organisation that decides why and how personal data is processed; a scraper that keeps names is one.

Legitimate interest The basis a scraper usually relies on for personal data, and it comes with a three-part test.

robots.txt A file asking crawlers what not to fetch; evidence everywhere, an opt-out in the EU, a law nowhere.