Glossary
Every term the courses use, defined in one line and then in a paragraph. Written to be read out of order.
Showing 9 of 124
Where jobs go after failing too many times.
A holding area for work that has repeatedly failed, so it stops consuming capacity and starts being visible. A queue system without one either retries forever or loses failures quietly.
Whether the mail you send reaches an inbox at all.
Sending is your side of it; delivering is the receiving provider’s decision, taken in a fraction of a second on the strength of what your domain says about you. Nothing in your code reports a failure here, which is why it is normally discovered by somebody who never got their password reset.
See also DNS, Transactional email, Bounce
Making new code live.
Build, upload, switch traffic, verify. During the switch two versions run simultaneously, which is why changes must be able to coexist with their predecessor for a few seconds.
Announcing that something will be removed.
Marking a field or endpoint as going away while still supporting it, so callers have time to move. Only meaningful if you can measure who is still using it.
See also Breaking change, Versioning
The system turning names into addresses.
Translates a domain name into the numeric address of a machine. Results are cached in many places you do not control, which is why a DNS change can take hours to be seen everywhere.
A database of flexible-shaped records.
Stores whole documents rather than rows with fixed columns. Related data is nested rather than joined. Suits genuinely independent records; fights you when your data is full of relationships.
The browser’s live model of the page.
The structure the browser builds from your HTML and then keeps in memory. JavaScript changes the page by changing the DOM. What you see in the elements inspector is the DOM, not your original HTML.
Saving what someone typed before they submit.
Keeping long-form input in browser storage as it is written, so an expired session or an accidental navigation does not destroy four paragraphs of work.
See also State, Validation
A confirmed write survives a crash.
The guarantee that once the database says it saved something, that remains true even if the power goes out a millisecond later. Harder than it sounds and a large part of what you pay a database for.
See also Transaction, Concurrency