IT Glossary
What is logging?
The practice by which applications record what they do in log files — the raw material for troubleshooting, audit and security investigation.
An aircraft has a flight recorder for the same reason an application needs logs: when something goes wrong, memory and opinion are worthless and a timestamped record is everything. Logging is the continuous writing of events as the software runs — a user signed in, an order was created, a payment provider returned an error, a scheduled job finished, a request took eleven seconds. Each entry carries a time, a severity and, when the design is good, an identifier that lets one customer transaction be followed across every system it touched. Three separate business needs draw on that record. Support answers the disputed complaint with what actually happened rather than with a plausible reconstruction. Auditors and regulators ask who accessed which personal data and when, and an unanswerable question is itself a finding. And security investigations depend entirely on the trail, because an intrusion is almost always discovered after the fact. The two failure modes are equally common and equally avoidable: keeping nothing, so the answers do not exist, and keeping everything indefinitely including passwords and personal data, which converts your logs into the most attractive target on the network.
Let’s talk about your project
Message us on WhatsApp or send an email — you talk directly to a developer.
office@northdan.com · +40 752 070 247
Why it matters for your business
Complaints resolved with evidence
A timestamped record settles what happened to an order or a payment, replacing an argument between two confident recollections.
Compliance demonstrable at audit
Access to personal data, administrative actions and system changes are traceable, which is what data protection audits actually ask for.
Attacks that leave visible traces
Centralised, tamper-resistant logs are what makes an intrusion detectable and its scope determinable rather than merely suspected.
Frequently asked questions
What logging levels exist and how are they used?
Conventionally five: debug for development detail, info for normal business events, warning for recoverable anomalies, error for failed operations, and critical or fatal for a system that cannot continue. Production usually runs at info with the ability to raise the level temporarily during an investigation. Logging everything at debug permanently is expensive and, paradoxically, makes finding the important entry harder.
How long should logs be retained?
Match the period to the purpose rather than to storage cost. Operational troubleshooting rarely needs more than thirty to ninety days at full detail. Security investigation benefits from six to twelve months, since intrusions are often discovered late. Financial and audit trails may be required for years by sector rules. Where logs contain personal data, GDPR requires a defined retention period and its enforcement, not indefinite accumulation.
Are logs allowed to contain personal data or passwords?
Passwords, card numbers, full tokens and health data must never be written to a log, and the frequent cause of leaks is an error handler dumping an entire request. Personal data may appear where it is necessary and justified, but then the logs inherit every GDPR obligation: lawful basis, retention limits, access control and inclusion in your processing records. Mask by default and log identifiers instead of contents.
Let’s talk about your project
Message us on WhatsApp or send an email — you talk directly to a developer.
office@northdan.com · +40 752 070 247