This counter is the aggregate total number of packets dropped by the router across all drop reasons. Because it's the sum of every specific drop counter in this table -- bad IP header, TTL expired, no route, no ARP entry, filtered, queue full, and more -- it's the single number to watch on a dashboard for overall link health, with a rising trend telling an admin to drill into the individual drop-reason counters to find which specific failure mode is responsible. A well-behaved link might drop only a handful of packets per hour, so seeing this counter jump by several thousand in a short window is the trigger to check the no-route or no-ARP-entry counters next for the specific cause.