What is data logging?
Definition
Data logging is the automatic recording of events or measurements over time. In security, a log is a chronological record of system activity, such as who accessed a system and what they did.
- Category
- Security
- Also called
- logging, event logging, log data
- Last updated
A log is a running diary a system keeps about itself. Each entry records something that happened and when: a login, a file opened, a setting changed, a failed password attempt. NIST's glossary defines an audit log as "a chronological record of system activities, including records of system accesses and operations performed in a given period", and, more simply, as "a record providing documentary evidence of specific events".
What gets logged
What ends up in a log depends on the system. A website might record the time of each visit, the page requested and the visitor's IP address. A work laptop might record sign-ins and software installs. A router might record which devices connected. Sensors and instruments log measurements (temperature, speed, location) the same way, which is where the term "data logger" comes from.
Why it matters for your privacy
Logs exist for good reasons: finding out what went wrong after an outage, spotting an attack, proving who did what. But a log entry that holds an IP address, a username or a device ID is information about a person, and it tends to sit in storage long after anyone looks at it. When a company is breached, old logs can leak along with everything else.
A typical example: you sign in to a shopping site from your phone. The site logs your account name, the time, your IP address and the device type. Those four details alone can show roughly where you were and when.
Logging vs. related terms
- Data mining looks for patterns in large piles of data. Logging is just the recording step that often feeds it.
- Telemetry is data sent back from software or devices about how they are used. It is usually written to logs on the receiving end.
- Tracking follows you across sites or apps. Logging records activity inside one system.
How to protect yourself
- 1
Check what a service keeps
Read the privacy policy section on retention. It should say what the company records about you and how long it keeps it. If the policy is vague, that is useful to know before you share more.
- 2
Use the privacy settings in your apps
Many apps and devices let you switch off diagnostic or usage reporting. Turn off what you don't need in the settings menu of your phone, browser and smart devices.
- 3
Ask for what a company holds on you
If you live in the UK or EU, you can ask a company for a copy of the personal data it holds about you, which can include log data tied to your account. Check the company's privacy page for the request route.
- 4
Reduce what a breach could expose
Logs that name you can leak in a breach. Use a different password for each account, and turn on two-factor authentication so a leaked sign-in record is less useful to an attacker.
See where your personal data is exposed
Serus finds it on data brokers and people-search sites and removes it.
Frequently asked
What is the difference between a log and an audit log?
A log is any automatic record of events. NIST describes an audit log as a chronological record of system activities, including accesses and operations, kept as evidence of what happened. In practice, audit logs are the logs kept for security and accountability.
Is data logging the same as spying on me?
Not by itself. Most logging is routine record keeping. It becomes a privacy concern when logs hold details that identify you and are kept for a long time or shared. The privacy policy of the service should tell you what it records.
What is a data logger?
A data logger is a device or program that records measurements or events over time, such as temperature readings or system activity, without someone writing each entry by hand.
Sources
Something wrong or out of date? Tell us and we'll re-check it.