IT words, explained

A computer that stays switched on so other people can reach it over the internet. Ours holds the video files and sends them to you when you press play. It is an ordinary computer doing an unglamorous job, not a magic box.

The internet's phone book. Computers only understand numbers, so DNS translates a name like karafa.net into the number that identifies the actual machine. Change which phone book you use and you can block adverts — that is exactly what the DNS guide does.

The number that identifies a device on a network, like 62.197.221.140. Your home has a public one given by your internet provider, and each device inside has a private one starting with 192.168. — which is why router settings pages live at addresses like 192.168.1.1.

The box from your internet provider that shares one internet connection with everything in your home and broadcasts the Wi-Fi. Because everything passes through it, changing a setting there affects every device at once.

How much data your connection can carry per second — the width of the pipe, not the speed of the water. A 4K film needs a much wider pipe than a phone video. When several people stream at once they share the same pipe, which is why everyone slows down together.

The pause when your device runs out of video to show because the connection cannot deliver it fast enough. Lowering the quality means less data per second, so a slower connection can keep up — that is why it is the standard fix.

Converting a video into a different format on the fly, because your device cannot play the original. It is the most expensive thing the server does — one transcoded stream can cost more than several normal ones. The opposite is direct play, where the file is sent untouched. Using a proper app instead of a browser usually avoids transcoding.

One video playing at one moment. Being logged in on five devices costs nothing; playing video on two at once is two streams. The limit on simultaneous streams is the one real restriction on a free account — see Live TV & motorsport.

How many dots make up the picture. Higher numbers look sharper but need far more bandwidth. On a phone, 720p is usually indistinguishable from 1080p; on a large television the difference is obvious.

Text of the dialogue shown over the picture. They are usually a separate track inside the file, which is why a title can have Slovak subtitles but not English, and why they can be switched off entirely.

A service that routes your internet traffic through another company's server, hiding your real location. Useful in general — but blocked here, because traffic arriving from VPNs cannot be told apart from abuse. Note that many ad blockers and "privacy" apps quietly run as a VPN, which is why people are blocked without realising they use one.

Scrambling data so only the intended recipient can read it. The padlock in your browser means the connection is encrypted. End-to-end encryption is stronger still: not even the server operator can read the contents, which is how Ghostline Chat works.

Ordinary DNS travels in the open, so whoever runs the network you are on can see every site name you look up. DNS over TLS encrypts those lookups. It is what Android's "Private DNS" and the Apple profile use.

A local copy kept so something does not have to be fetched again. It makes things fast, but it is also why a change you just made appears not to have worked — the device is still using the old copy. Restarting usually clears it.

The free, open-source software that runs the media library — the thing you actually log into at jellyfin.karafa.net to browse and play films.

The request system at req.karafa.net. You ask for a film there and the server fetches it automatically. You can also request from inside Jellyfin itself — see the requests guide.

The tool that handles invitations. You visit wizarr.karafa.net exactly once, using a link we send you, to create your account. After that you never return to it — you log in at jellyfin.karafa.net. Confusing these two is the most common mistake new users make.

A phone app for watching from the library — an alternative to the official Jellyfin app, with requests built in and offline downloads. See the phone guide.

Three layers of the same chat service. Matrix is the open standard, Element is the app you use, and Ghostline is the name of the server we run at element.karafa.net.

Software that checks every few seconds whether each service is responding, and records the result. That is what status.karafa.net shows — so you can tell whether a problem is ours or yours.

A way of packaging a program with everything it needs so it runs in isolation from the rest of the machine. Each service here runs in its own container, which is why one of them can break without taking the others down.

The doorman for the whole server. All web traffic arrives at one program (nginx), which checks it, handles the encryption, and passes it to the right service behind the scenes. It is also what shows you the "Proxy detected" page.

An uninterruptible power supply — a large battery between the wall and the servers. When the electricity fails, everything keeps running on battery instead of dropping dead, which is how the infrastructure survives local power cuts.

Sending video from your phone to a TV over Wi-Fi. The phone acts only as a remote control — the video travels straight from the server to the TV, so you can lock your phone without stopping playback.

An app that generates and remembers a different strong password for every site, so you only memorise one. The single most effective security habit there is, and the easiest one to adopt.

A Jellyfin feature that lets you sign in on an awkward device — a TV, a games console — by typing a short code on your phone instead of tapping out a password with a remote control.