Architecture: Technique for supporting structures, particularly roofs.

Post and lintel is the simplest form of roofing support, where elements are simply placed on top of one another, with no structural binding:

             /\
            /||\
           / || \    <- roof
          /  ||  \
         /   ||   \
         ==========  <- lintel
         ||  ||  ||
         ||  ||  ||   <- posts
         ||  ||  ||

Compare this to a truss roofing structure, where the roof is part of an independent triangular unit resting on an architrave:

             /\
            /  \
           /    \    <- roof (note the triangular structure)
          /      \
         /________\
         ==========  <- architrave
         ||      ||
         ||      ||  <- posts
         ||      ||

Note that fewer posts are needed with a truss roof, because the peak is supported by the inherent structure of the truss.

Post and lintel roofing structures were extensively used by the ancient Greeks, who were not aware of the truss.