Backup
A separate copy of data that you can restore it from after a loss.
Example A 3-2-1 backup: three copies, two types of storage, one kept away from home.
Not to be confused withSync
Eberprot P / glossary
Glossary
Short definitions without circular references: what a term means, where you'll come across it and what it's often confused with.
B
C
Checksum (hash)
A short string calculated from a file's contents; any change to the file changes it.
Example The SHA-256 of the string "hello" followed by a newline starts with 5891b5b5.
Not to be confused withEncryption
D
DNS
The system that translates a domain name (example.com) into a server's IP address.
Example If websites won't load but pinging an IP address works, DNS is often to blame.
Not to be confused withIP address
E
Encryption
A transformation of data that can only be reversed with a key.
Example An encrypted backup archive can only be opened with the password.
Not to be confused withChecksum (hash)
H
HTTP status code
A three-digit server response code: 200 — success, 301 — permanent redirect, 404 — not found, 410 — permanently removed.
Example curl -I shows a page's status without downloading it.
HTTPS
HTTP secured with TLS encryption: data between the browser and the website can't be read in transit.
Example The padlock icon means encryption, not that the site is honest: phishing sites can have HTTPS too.
Not to be confused withVPN
I
IP address
A numerical address for a device on a network, such as 192.168.1.1 on a home network.
Example A router's address on a home network usually starts with 192.168.
Not to be confused withDNS
M
Malware
Software that works against the interests of the device's owner: it steals data, encrypts files or displays ads.
Example A Trojan hidden inside a "free" game cheat.
Not to be confused withPhishing
P
Passkey
A passwordless sign-in method based on the FIDO standard: the device stores a secret key and confirms the sign-in with a fingerprint, face or PIN.
Example Signing in to a website with Face ID instead of typing a password.
Not to be confused withTOTP
Phishing
A scam that persuades a user to enter their details on a fake website or to share a code.
Example An email saying "your account has been suspended" with a link to a lookalike address.
Not to be confused withMalware
S
Sync
Keeping files identical across several devices — including deletions.
Example You delete a file on your laptop, and it disappears from the cloud too.
Not to be confused withBackup
T
TOTP
A one-time code that an app calculates from a secret key and the current time (RFC 6238 standard).
Example The six-digit code in an authenticator app, which usually changes every 30 seconds.
Not to be confused withTwo-factor authentication (2FA)
Two-factor authentication (2FA)
A sign-in that requires a second confirmation in addition to the password: a code, a key or approval on a device.
Example A code from an authenticator app after entering your password.
Not to be confused withTOTP
V
VPN
An encrypted tunnel between your device and a VPN server; websites see the server's address instead of yours.
Example A VPN protects your traffic on public Wi-Fi, but it won't save you from entering your password on a phishing site.
Not to be confused withHTTPS
Sources and verification
- RFC 9110: HTTP Semantics (status codes)
- RFC 6238: TOTP
- FIDO Alliance: about passkeys
Software and service interfaces change. We list the versions we tested commands on; on other versions the steps may differ.