Glossary
Every term the courses use, defined in one line and then in a paragraph. Written to be read out of order.
Showing 10 of 124
A spreadsheet with a strict header.
Rows are things, columns are facts about them, and every row has the same columns with declared types. That strictness is what lets the database refuse bad data.
See also Primary key, Schema, SQL
A hard limit on how long something may take.
Enforced by browsers, proxies, and serverless platforms. Work that exceeds one is killed partway through, leaving whatever it was doing half-finished.
See also Background job, Retry
The encryption behind the S in HTTPS.
Makes the connection private and tamper-proof. Without it, anything between the user and your server can read and modify the page. Costs an extra handshake on the first connection.
A string that proves something about you.
A credential passed with requests to identify or authorise the holder. Anyone holding it can use it, which is why tokens are short-lived and kept out of reach of page scripts.
The unit models read, write, and charge by.
Roughly three quarters of a word. Everything meters in tokens: cost, the context window, and how long a response takes to produce.
See also Context window, Prompt caching
Letting a model call functions you define.
Giving a model a set of actions it may take: search, fetch, create. Turns a text generator into something that affects the world, which makes what you grant far more important than how well it reasons.
See also Agent, Blast radius
Following one request across every system it touches.
A timed record of a single request as it moves between services. When four systems are involved and something is slow, a trace identifies the culprit in seconds instead of hours.
See also Logs, Metrics, Observability
All of these changes, or none of them.
A group of changes applied as one unit. Without it, "take money from A" can succeed while "give money to B" fails. Any operation touching two things at once needs one.
See also Durability, Integrity, Concurrency
Mail sent because a user just did something.
Password resets, receipts, confirmations: expected within seconds by a person who is waiting for them. Distinct from marketing mail, which goes out on your schedule and needs consent. Mixing the two costs you the reputation that gets the urgent one delivered.
See also Deliverability, Consent, Bounce
How long a cached copy stays valid.
Time to live: the expiry on a cached item. Simple to reason about, at the price of accepting staleness up to that duration.
See also Cache, Invalidation