Membrane Electrode Gas Diffusion Layer segmentation by type distinguishes three principal material families: carbon‑based, metallic, and composite layers. Carbon‑based GDLs, typically composed of carbon paper or cloth impregnated with PTFE, dominate the market due to their low cost, high electrical conductivity, and established supply chain, accounting for roughly 60 % of total shipments. Metallic GDLs, constructed from stainless steel or nickel meshes, offer superior mechanical robustness and thermal conductivity, positioning them in niche high‑temperature or high‑pressure fuel‑cell designs; they represent about 15 % of the market. Composite GDLs combine carbon fibers with polymer binders or metal nanostructures to balance conductivity, water management, and durability, capturing the remaining 25 % as OEMs adopt them for next‑generation PEM and electrolyzer stacks. Consequently, the cost advantage of carbon‑based GDLs drives volume growth in automotive PEM fuel‑cell programs, while the durability premium of metallic and composite GDLs supports higher‑margin segments such as stationary power and offshore electrolyzers.