Pillar 1 - Free Reference

Tech Glossary explained for humans.

73+ tech and AI terms defined in 1-2 sentences. No jargon-on-jargon definitions. If a definition isn't clear, email us at hi@tech-sensei.com.

A

2FA (Two-Factor Authentication): Login requires two separate pieces of evidence: something you know (password) + something you have (phone code, hardware key). Stops 99% of automated account takeovers.
Affiliate link: A URL that includes a tracking parameter, so the merchant knows the visitor came from a specific site. Site earns commission on sale; visitor pays the same price.
AI agent: An AI program that can take multi-step actions (browse, write, code) toward a goal, not just answer questions. As of 2026: capable but unreliable for high-stakes tasks.
AI Overview: Google's AI-generated answer at the top of search results. Replaces some traditional blue links. Big impact on traffic for content sites.
Antivirus: Software that scans files and processes for malicious code patterns. In 2026 less critical than 10 years ago (Windows Defender is solid), still useful for vulnerable users.
API (Application Programming Interface): The contract by which one program talks to another. When you connect Zapier to Slack, you're using an API.

B

Backup: A copy of your data stored separately from the original. Rule 3-2-1: 3 copies, 2 different media, 1 off-site.
Bandwidth: The maximum data transfer rate of an internet connection (e.g., 100 Mbps = 100 million bits per second). Higher = faster downloads.
Brute force attack: An attacker tries every possible password combination until one works. Defeated by strong passwords (entropy) and account lockouts.

C

CAPTCHA: "Completely Automated Public Turing test to tell Computers and Humans Apart". The annoying click-the-buses test.
Captcha bypass: AI tools now solve CAPTCHAs faster than humans. This is reshaping the bot-vs-human web war.
Cloud storage: File storage hosted on remote servers (Dropbox, iCloud, Google Drive, Proton Drive). Convenient but you trust the provider.
Cookies: Small data files stored by your browser. Functional cookies (login session) are necessary; tracking cookies (advertising) are the privacy concern.
Cryptocurrency: Digital currency secured by cryptography. Bitcoin, Ethereum are the major ones. Beyond Tech Sensei scope mostly.
Cyber hygiene: Routine practices that keep your digital life safe: update software, use strong passwords, enable 2FA, recognize phishing.

D

Data breach: An incident where private data is exposed to unauthorized parties. Check yourself at haveibeenpwned.com.
DNS (Domain Name System): The phonebook of the internet: translates "google.com" into "142.250.190.78". Cloudflare 1.1.1.1 is a fast privacy-friendly DNS.
DDoS (Distributed Denial of Service): An attack that floods a server with traffic from thousands of devices, taking the service offline. Affects merchants, not usually end users.
Dark mode: Inverted color scheme for screens (dark background, light text). Reduces eye strain at night, may save battery on OLED screens.

E

E2EE (End-to-End Encryption): Messages encrypted on sender device, decrypted only on recipient device. Server in middle sees only encrypted blob. Signal, ProtonMail do this; Gmail doesn't.
Encryption: Mathematical scrambling of data so only those with the key can read it. AES-256 is the current consumer standard.
Ethernet: Wired network connection (vs Wi-Fi). Faster and more reliable for fixed devices.
Exploit: A specific technique to abuse a software vulnerability. Patched by software updates.

F

Firewall: Software or hardware that blocks unauthorized network traffic. Built into Windows and macOS by default; mostly invisible to end users.
Firmware: Software embedded in hardware devices (router, smart bulb, USB drive). Should be updated when manufacturer releases patches.
Phishing: Fraudulent attempt to obtain credentials by impersonating trusted entity (bank, IT department) via email or message. 90%+ of breaches start with phishing.

G

GDPR (General Data Protection Regulation): EU privacy law (2018) giving users rights over their data. Applies to any company processing EU citizen data.
GPU (Graphics Processing Unit): Specialized processor for graphics, also used for AI training. NVIDIA dominates this market.

H

Hardware key: Physical 2FA device (YubiKey, Google Titan). Strongest form of 2FA, immune to phishing.
HTTPS: Encrypted HTTP. Padlock in address bar = HTTPS = traffic encrypted between your browser and the server. Essential for any login.
Hash: One-way mathematical function: given input, produces fixed-length output that can't be reversed. How passwords are stored properly.

I

IDS (Intrusion Detection System): Monitors network for suspicious patterns. Built into enterprise networks; rarely needed for consumer setups.
IoT (Internet of Things): Network-connected physical devices: smart bulbs, thermostats, cameras, door locks. Massive attack surface if not secured.
IP address: Numeric identifier of a device on a network. IPv4 (192.168.1.1) running out; IPv6 (2001:db8::1) is the future.

L

LLM (Large Language Model): AI model trained on massive text corpus to predict next tokens. ChatGPT, Claude, Gemini are LLM-based chatbots. Not "AI" in sci-fi sense.
Local-first: Software architecture where data lives primarily on user's device, not cloud servers. Obsidian, Logseq follow this.

M

Malware: Umbrella term for malicious software: viruses, ransomware, spyware, trojans, worms.
Matter: Smart home standard (2022+) that lets devices from different vendors work together. Aqara, Eve, Apple, Google all support Matter.
MFA (Multi-Factor Authentication): Same as 2FA but more factors possible: knowledge + possession + biometric + location.
Mesh Wi-Fi: Multi-node Wi-Fi system that creates a single network covering large homes. Eero, Asus AX, Google Nest Wifi are examples.

N

NAS (Network Attached Storage): A small home server for storage + media + backups. Synology and QNAP are the popular brands.
Network neutrality: Principle that ISPs should treat all internet traffic equally. Politically contested in different countries.
No-logs policy: A VPN provider's promise not to record user activity. Verified by external audits (PwC, Deloitte) for major VPNs.

O

Open source: Software with publicly accessible source code. Allows security audits, modifications, self-hosting.
OS (Operating System): Foundation software: Windows, macOS, Linux, iOS, Android.
OTP (One-Time Password): Single-use code, often time-based (TOTP). What Google Authenticator generates.

P

Password manager: Encrypted vault for storing unique passwords. Generates strong passwords, autofills logins. Bitwarden, 1Password, KeePassXC.
Passkey: Modern replacement for passwords. Uses public-key cryptography + biometric unlock. iOS 16+, Android, modern browsers support.
Patch: Software update that fixes a vulnerability or bug. "Patch Tuesday" = Microsoft's monthly update cycle.
PII (Personally Identifiable Information): Data that identifies a person: name, email, SSN, biometrics. Heavily regulated under GDPR + CCPA.
Privacy policy: Legal document explaining what data a service collects and how it uses it. Usually too long; should be reviewed for sensitive services.

R

Ransomware: Malware that encrypts your files and demands payment for decryption key. Backups are the only reliable defense.
RAT (Remote Access Trojan): Malware that gives attacker remote control of your device. Often delivered via phishing.
Router: Device that connects your home network to the internet. Quality varies; ISP-provided routers are often weak.

S

Scam: Fraudulent scheme to extract money or data. In tech: fake invoices, fake support calls, romance scams.
Self-hosting: Running services on your own hardware (Synology, Raspberry Pi). Privacy benefit, complexity cost.
SIM swap: Attacker convinces phone carrier to transfer your phone number to their SIM. Bypasses SMS-based 2FA. Use app-based 2FA instead.
Smart home: Network of connected home devices: lights, locks, thermostats, speakers, cameras.
Smishing: Phishing via SMS. Often impersonates banks or shipping companies.
Spyware: Software that secretly observes user behavior. Includes stalkerware (intimate partner abuse) and commercial tracking.
SSL/TLS: Cryptographic protocols underlying HTTPS. TLS 1.3 is current standard.
SSO (Single Sign-On): "Login with Google" / "Login with Apple". One credential unlocks many services. Convenience + centralized risk.

T

Thread: Smart home networking protocol (radio). Used by Matter alongside Wi-Fi and Bluetooth.
TOTP (Time-based One-Time Password): 2FA codes that rotate every 30 seconds. Authy, Google Authenticator, 1Password TOTP.
Tor: Anonymity network that routes traffic through multiple servers. Used by journalists, activists, criminals. Not the same as a VPN.
TPM (Trusted Platform Module): Hardware security chip in modern computers. Stores cryptographic keys safely.

U

USB Restricted Mode: iOS feature that disables USB data connection after 1 hour of being locked. Defeats police-grade forensic tools.

V

VPN (Virtual Private Network): Encrypts your internet traffic between your device and a VPN server. Hides traffic from ISP and public Wi-Fi snoops.
Vulnerability: A flaw in software that can be exploited. Discovered by security researchers, patched by vendors.

W

WireGuard: Modern fast VPN protocol. Replaced OpenVPN as the default for most VPN apps.
Wi-Fi 6 / 7: Current and next Wi-Fi standards. Wi-Fi 6 (AX, 2019) common in 2026; Wi-Fi 7 (BE, 2024) cutting-edge.

Z

Zero-day: A vulnerability that attackers know about before the vendor does (or before a patch exists). Most serious type of vulnerability.
Zero-knowledge: Architecture where the service can't access user data even if it wanted to. ProtonMail, Bitwarden, Signal use this.

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