Glossary
The words, defined
AI user testing borrows words from research, QA and AI, and uses some of them loosely. These are the definitions we work from, each with the point where it stops being true.
- Agent experience (AX)
- Agent experience is how well an AI agent can use a product on someone’s behalf: find what it needs, understand the page, and finish the task without a person stepping in. Read more about Agent experience (AX)
- AI user testing
- AI user testing sends AI agents with defined personas through a product in place of recruited participants, and reports what each one did and where it got stuck. Read more about AI user testing
- Browser agent
- A browser agent is an AI model that operates a web browser: it reads the page, decides on an action such as a click or a keystroke, performs it, and repeats until the task is done. Read more about Browser agent
- llms.txt
- llms.txt is a plain-text Markdown file at the root of a website that tells language models what the site is and links to the pages worth reading, in a form that is cheap to fetch and parse. Read more about llms.txt
- Model Context Protocol (MCP)
- The Model Context Protocol is an open standard for connecting AI assistants to tools and data. A service exposes an MCP server, and any MCP client, such as Claude or Cursor, can call its tools. Read more about Model Context Protocol (MCP)
- Prototype testing
- Prototype testing puts an unfinished design in front of users to see whether they can complete the key tasks before anything is built. Read more about Prototype testing
- Sycophancy in synthetic research
- Sycophancy is the tendency of language models to tell the person asking what they seem to want to hear. In synthetic research it shows up as simulated users who like every concept they are shown. Read more about Sycophancy in synthetic research
- Synthetic research
- Synthetic research is user research run with AI participants instead of recruited people: interviews, usability tasks and studies where the participants are personas played by AI agents. Read more about Synthetic research
- Synthetic users
- Synthetic users are AI agents given a persona (a background, goals and constraints) that stand in for real users in research or testing. Read more about Synthetic users
- Usability testing
- Usability testing watches people attempt real tasks in a product to find where they hesitate, make mistakes or give up. Read more about Usability testing
- User persona
- A user persona is a profile of a type of person a product serves: who they are, what they are trying to do, what they know already and what gets in their way. Read more about User persona
- UX regression testing
- UX regression testing checks, after every change, that the flows users depend on still work and still make sense, not only that the code still passes. Read more about UX regression testing