EN 10365 is the European standard that establishes the nominal cross-sectional dimensions and unit masses for hot-rolled steel I-sections, H-sections, and channels. Published by CEN in January 2017 through technical committee CEN/TC 103, it superseded the long-standing German standards DIN 1025 (beam profiles) and DIN 1026 (channel profiles), while also incorporating several British section families — including UB, UC, HP/UBP, HD, HL/HLZ, PFC, and J series — that had never been part of the traditional DIN system. The standard defines nominal geometry and mass per meter for hot-rolled carbon steel sections, but deliberately excludes dimensional tolerances, corner radii, and section properties, which are governed by separate standards. By consolidating beams and channels into a single document and integrating the British profile families, EN 10365 created a unified European framework for structural steel sections. The current active version is EN 10365:2017, with a revision already under development at the CEN committee level.