Hardware (HW) maintenance contracts for data center and network equipment may cover hardware replacement, on-site field engineering, technical support and proactive monitoring. The focus of this market is on the independent, third-party market for data center and network maintenance. This is maintenance provided independently from the OEMs, often referred to as "TPM" (third-party maintenance), "unauthorized maintenance" or "alternative maintenance." A hybrid maintenance strategy — using OEM-authorized and OEM-independent maintenance — is becoming more common in the hardware support market, with a thriving ecosystem of independent support providers for server, storage and networking equipment. End-user customers are selectively using TPMs to cost-effectively extend the life of IT assets, control OEM-forced upgrades, and save money.