GlossaryServer log
What is server log?
A server log (or access log) is the file a web server or CDN writes with one line per request it answered: time, path, status, client IP, user agent and referrer. It is the only record that includes every visitor, human or not, whether or not they ran any script.
Also called: access log, CDN log, edge log.
Web analytics works from the other end: a script in the page that runs in the visitor’s browser and sends an event. Anything that does not run the script is invisible to it: every AI agent, every crawler, every link unfurler, and every person with an ad blocker. The server log has all of them, because it is written by the server, not the visitor.
Most hosting already writes one. CloudFront writes standard logs to an S3 bucket, nginx and Apache write access logs in the common or combined format, and other CDNs offer log delivery. Because the log already exists, it can be analysed for last month today, which no script-based tool can do.
Logs contain IP addresses, which is personal data. agenttraffic reads them in memory to verify agents and estimate distinct visitors, and never writes them out.
Related terms
- AI agent: An AI agent is any automated visitor that fetches web pages on behalf of an AI product: the crawler that collects training data, the crawler that builds an AI search index, and the fetcher that reads a page live while a person is talking to an assistant..
- Dark social: Dark social is sharing that analytics cannot attribute: links passed in private messages, chat apps, email and text, which arrive with no referrer and get filed under "direct" traffic..
- Bot verification: Bot verification is checking that a request claiming to be a known bot really came from its operator, by comparing the request’s IP address with the addresses the operator publishes, or by reverse DNS when no list exists..
Published 2026-09-21, updated 2026-09-21.