The 0.100" (2.54 mm) pitch is the classic industry-standard spacing, which means it fits legacy footprints and common perf-board patterns without a layout change.
Rated 5 A per contact — that is typical for a 0.100" pitch pin header and gives enough headroom for signal lines plus moderate power distribution on the same connector. The 30.0 µ" (0.76 µm) gold or GXT™ plating on the mating surface is the spec that matters for field reliability: that thickness supports repeated mating cycles and resists corrosion in industrial cabinets or unsealed enclosures. The tin-plated solder tails are standard for wave-solder assembly.