IPv4 rental is straightforward: sign a rental agreement (monthly or annual), provider allocates IPs from their pool, you announce IPs via BGP or use provider's infrastructure, pay monthly until you cancel, IPs return to provider when done. You get usage rights (not ownership), BGP announcements, basic support, and flexibility to scale up or down. Current prices: $0.40-0.60 per IP per month for /24 blocks. Hidden costs to watch: setup fee ($50-200), BGP configuration ($100-300 if not included), early termination (2-3 months' rent).