Glossary

Plain-English definitions. Scenario pages link here from "Terms in this scenario".

.gitignore: A file listing patterns Git should never track (node_modules/, .env, build output).
Branch: A movable label pointing at a commit. Branches let you work on something without touching main.
Build: The step where Vercel runs your build command (e.g. npm run build) to produce the files it serves.
Clone: Download a full copy of a remote repository, history included, and set origin for you.
Commit: A saved snapshot of your project with a message and a unique ID. Commits are the steps in your history.
Detached HEAD: You checked out a commit instead of a branch. Anything you commit can get lost unless you create a branch from it (git switch -c name).
Environment variable: A named setting (API key, URL) kept outside your code. On Vercel they are set per environment in project settings.
EPS (events per second): The average number of log messages arriving each second. Multiply by message size and time to size disk.
Facility: A syslog label (0 to 23) saying which part of a system produced the message, e.g. auth or local7. Part of the priority number.
Fast-forward: A merge where your branch has no new commits of its own, so Git just moves the pointer forward. No merge commit is needed.
Fetch: Download the latest commits from the remote without changing your files. Safe to run any time.
Force push: Overwrite the remote branch with your local one. Prefer --force-with-lease, which refuses if someone else pushed in the meantime.
Git Credential Manager: The helper bundled with Git for Windows that signs you in to GitHub in the browser and stores the token in Windows Credential Manager.
HEAD: A pointer to where you are now, usually the latest commit of the branch you are on. HEAD~1 means one commit before it.
main: The default branch name in modern Git/GitHub. Vercel treats it as the production branch by default.
Merge: Combine the history of two branches. Git creates a merge commit unless it can simply fast-forward.
Merge conflict: Git cannot combine two edits to the same lines automatically. You choose the final text, then git add and commit.
origin: The default nickname for the remote you cloned from or first connected (your GitHub repo).
Preview deployment: A temporary Vercel site built from any non-production branch or pull request, with its own URL.
Production deployment: The live site, built when you push to the production branch (normally main).
Pull: Fetch plus merge (or rebase): download remote changes and combine them into your current branch.
Pull request (PR): A GitHub page proposing to merge one branch into another, with review and checks. Vercel builds a preview for each one.
Push: Upload your local commits to the remote branch.
Rebase: Replay your commits on top of another branch to get a straight-line history. It rewrites commits, so avoid it on commits you already pushed and shared.
Reflog: A private log of everywhere HEAD has been. It is the safety net for recovering "lost" commits.
Remote: A copy of the repository hosted elsewhere, such as GitHub.
Repository (repo): A project folder tracked by Git. It holds your files plus the hidden .git folder that stores the full history.
Reset: Move the current branch back to an earlier commit. --soft keeps changes staged, --mixed unstaged, --hard throws them away.
Revert: Make a new commit that undoes an older one. Safe for commits that are already pushed.
Severity: A syslog level from 0 (emergency) to 7 (debug) saying how serious a message is. Priority = facility x 8 + severity.
SIEM: Security Information and Event Management: a platform that collects logs, correlates events and raises security alerts (for example Wazuh, Splunk ES, Sentinel).
SSH key: A key pair used instead of a password to authenticate with GitHub. The private half never leaves your computer.
Staging area (index): A waiting room between your edits and a commit. git add puts changes there; git commit saves exactly what is staged.
Stash: A shelf for uncommitted changes. Put work aside with git stash, bring it back with git stash pop.
Syslog: A standard message format and network protocol for sending log messages from devices to a central server. Classic port is 514.
Syslog server: Software on a machine that listens for syslog messages (usually UDP/TCP 514) and stores them. Examples: rsyslog, syslog-ng, Kiwi Syslog.
Tag: A permanent label on a commit, usually used for releases such as v1.0.0.
Upstream branch: The remote branch your local branch tracks, e.g. origin/main. Once set, plain git push and git pull know where to go.
Working tree: The actual files in your folder right now, including edits that are not committed yet.