What is the IAB Spiders and Bots List?
The IAB/ABC International Spiders and Bots List is a regularly updated list of known crawlers, bots and automated user agents, maintained by the IAB and ABC UK. Ad servers and measurement companies use it to filter known non-human traffic out of impression and click counts. It is a basic general invalid traffic (GIVT) filter referenced in MRC guidelines.
The IAB/ABC Spiders & Bots List catches self-declared bots: search-engine crawlers, feed readers, monitoring services and other automation that identifies itself in its user agent. Because honest bots announce themselves, the list is effective for GIVT but does nothing against fraudulent bots that disguise themselves.
Access requires a paid licence, and it is widely built into ad servers. Using it is part of MRC accreditation requirements and TAG Certified Against Fraud, but it should be one layer among many.