IP transit is the service through which a carrier transports your traffic to the whole Internet: it announces your prefixes to the rest of the world and delivers full BGP routes (or a default route). It is the opposite of peering, which only exchanges traffic between two networks.
Two billing modes: per port (fixed capacity, e.g. a full 1 Gbps) or 95th percentile (you pay for actual usage, the top 5% of peaks discarded). Benchmarks from our catalog: 150–400 €/month for 1 Gbps, 420–950 € for 10 Gbps — the per-megabit price collapses with volume.
For resilience, take two distinct transit providers (BGP multi-homing) or, without your own AS, a carrier present at both your sites: your IP addresses then follow to the backup site without renumbering.