Glossary · Security

Data Breach

A data breach is an incident in which confidential, protected or personal data is accessed, disclosed or stolen by someone not authorized to have it.

Updated October 6, 2026

A data breach is a security incident where sensitive information, such as customer records, credentials or financial details, is accessed, copied or exposed without authorization, whether through attack, error or insider misuse.

Why it matters

Breaches cause financial loss, regulatory penalties and lost trust, and leaked credentials fuel further attacks like credential stuffing. Laws such as GDPR require notifying regulators, and sometimes affected individuals, within set timeframes. Prevention combines patching, access control, encryption and monitoring, backed by an incident response plan.

Example

A misconfigured cloud storage bucket is left public, exposing a customer export file. No hacking was needed, yet it is a breach. Users should change reused passwords and watch for phishing that uses the leaked details.

Common mistakes

  • Assuming breaches only come from sophisticated hackers. Misconfiguration and mistakes are common.
  • Delaying notification while investigating beyond legal deadlines.
  • Keeping data you no longer need, which increases what can leak.

Get notified when this term updates

Plus occasional practical tips on uptime and monitoring, nothing else. Unsubscribe anytime.

Keep reading

Glossary · SecurityBot ManagementBot management is the set of techniques that identify automated traffic and decide whether to allow, challenge, slow or block it.Glossary · SecurityMalwareMalware is any software deliberately designed to damage systems, steal data or gain unauthorized access, including viruses, trojans, ransomware and spyware.Glossary · SecurityPhishingPhishing is a social engineering attack that uses fake emails, messages or websites to trick people into giving up credentials, money or access.Guide · EmailCheck Your Email Domain Setup (MX, SPF, DKIM, DMARC) in 15 MinutesA beginner's walkthrough to check that your business email domain has the right MX, SPF, DKIM and DMARC records, with free tools and plain-language fixes.7 min readGuide · E-commerceE-commerce Order Email Deliverability: Why Confirmations Go MissingMake order confirmations and shipping emails reach inboxes: SPF, DKIM, DMARC, sender setup for Shopify and WooCommerce, testing, bounces and monitoring.7 min readGuide · E-commerceE-commerce Site Security Checklist: 30 Checks for Online StoresA practical security checklist for online stores covering HTTPS, headers, payment pages, third-party scripts, admin access, updates, backups and monitoring.7 min read

This page is general information written by our editorial team and updated when documentation changes. Servers and providers differ, so test changes safely first. See our editorial policy and disclaimer.