XDP, or eXpress Data Path, is a Linux networking feature designed to enhance high-performance packet processing by running programs in the kernel, specifically before packets reach the kernel's network stack. Built on the extended Berkeley Packet Filter (eBPF), XDP allows for faster processing by handling packets as soon as they arrive at the network interface card (NIC), enabling actions like dropping, redirecting, or retransmitting packets through predefined return codes. These programs are attached to NICs and can operate in native, offloaded, or generic modes, with offloading offering the best performance when supported by SmartNICs. XDP’s efficiency is particularly beneficial for applications such as DDoS protection, firewalls, and load balancers, and can be implemented using libraries like the BPF Compiler Collection (BCC). The feature's ability to work safely in kernel space after code verification makes it a valuable tool for developers aiming to build observability tools and network performance solutions.