Equalization training is a process used in PCI Express (PCIe) links to optimize signal quality and ensure reliable high-speed data transmission. During equalization training, the transmitter and receiver communicate to adjust signal parameters such as amplitude and timing. This process compensates for signal degradation caused by channel imperfections, such as loss or interference, that can occur over long distances or at high frequencies. By dynamically tuning these parameters, equalization training helps maintain data integrity and reduces the likelihood of transmission errors. The process is typically performed when a PCIe link is initialized or when link conditions change, ensuring optimal performance and stability throughout the connection.