Glossary

A snapshot is a frozen picture of a disk or system at one moment that you can roll back to if something goes wrong.

A branch is a separate line of work in Git, so you can try changes without touching the main version of the project.

A certificate is a digital ID card that proves a website or server is genuine, issued by a trusted authority.

A cluster is a group of computers working together as one system so that if one fails the others keep the service running.

A commit is a saved snapshot of your project in Git, with a message explaining what changed and why.

A container is a lightweight box that packs a program with everything it needs so it runs the same on any computer.

A cookie is a small piece of text a website stores in your browser so it can recognise you on the next request.

A cron job is a command scheduled to run automatically at set times, such as every night at two o'clock.

A daemon or service is a program that runs in the background all the time, waiting to do its job without a user watching.

A database is an organised store of data that programs can search, update and share safely, even with many users at once.

A dependency is another piece of software your program needs to work, such as a library it imports.

A detection rule describes one kind of suspicious activity in logs. Sigma is the shared, tool-independent way to write such rules, so teams can exchange detections and convert them for whatever log system they run.

A firewall is a filter that decides which network connections are allowed in or out of a computer or network.

A foreign key is a column that points to the primary key of another table, linking related rows together.

A hypervisor is the software layer that creates and runs virtual machines and shares the real hardware between them.

A log is a running record of what a program did and when, written to a file so you can look back when something breaks.

A merge conflict happens when two branches changed the same lines and Git needs a human to decide which version wins.

A package manager is a tool that installs, updates and removes software for you and keeps track of what depends on what.

A pod is the smallest unit Kubernetes runs: one or more containers that share a network address and storage.

A port is a numbered door on a computer that lets one machine run many network services at the same time.

A primary key is the column that uniquely identifies each row in a table, like an ID number nobody else can have.

A process is a running program; the operating system gives each one its own memory and an ID number.

A pull request asks teammates to review and merge the changes on your branch into the main branch.

A REST API is a web API where you use normal HTTP requests on URLs to read, create, update and delete things.

A reverse proxy is a server that sits in front of your apps, receives all requests and forwards them to the right one.

A shell is the program that reads the commands you type and tells the operating system to run them.

A status code is the three digit number a web server returns to say whether a request worked, like 200 OK or 404 Not Found.

A terminal is the window where you type commands; the shell inside it does the actual work.

A token is a string that proves who you are or what you may do, sent with requests instead of a password.

A transaction groups several database changes so they all happen together or not at all, keeping the data consistent.

A virtual environment is a private folder of Python packages for one project, so different projects never clash.

A virtual machine is a complete computer made of software, running inside another computer with its own operating system.

An API is a set of rules that lets one program ask another program for data or actions without knowing how it works inside.

Awesome lists are hand-curated link collections on GitHub, one per subject, that follow a shared convention. How they work, how to tell a maintained one from an abandoned one, and how to use them without getting lost.

An environment variable is a named value the operating system passes to programs, such as settings or secrets.

A database index is a lookup structure that lets the database find rows fast instead of reading the whole table.

An IP address is the unique number that identifies a device on a network so data knows where to go.

CI/CD is the habit of automatically testing every code change and, once it passes, deploying it without manual steps.

CORS is a browser rule that decides whether a web page from one site is allowed to call an API on another site.

DNS is the internet's phone book: it turns names like example.com into the IP addresses computers actually use.

Encryption scrambles data with a key so only someone with the right key can read it again.

Hashing turns any data into a fixed length fingerprint that cannot be reversed, used to check files and store passwords.

HTTP is the request and response language that browsers, apps and servers use to exchange web pages and data.

JSON is a simple text format for structured data, made of names, values, lists and nested objects, used everywhere on the web.

Kubernetes is a system that runs containers across many servers, restarting, scaling and connecting them automatically.

Open source software is software whose code anyone can read, change and share under a licence that allows it.

Oracle Private Cloud Appliance is a factory-built rack of compute, storage and network hardware with its own cloud software. Release 3.x offers an OCI-compatible cloud; the older 2.x line is based on Oracle VM.

PATH is the list of folders your shell searches to find a program when you type its name.

RAID combines several disks into one so data survives a disk failure or is read and written faster.

SQL is the language you use to ask a relational database questions and to add, change or delete its data.

SSH is a secure way to open a command line on another computer over the network, with everything encrypted.

TLS is the encryption layer that puts the S in HTTPS, protecting data between your browser and a server.

YAML is a human friendly text format for configuration files where indentation shows structure instead of brackets.