AbuseIPDB is a free, community-driven IP reputation service. Analysts submit abuse reports (SSH brute-force, web scanning, spam, DDoS) and consumers query the API to get a confidence score (0-100) and category breakdown for any IP.
For a SOC analyst it is the fastest OSINT enrichment step during triage: paste a suspicious source IP from a firewall or SIEM event, and within seconds you know whether the wider community has already flagged it — and for what.