A lintel is a beam that is placed above windows and doors. The lintel's main job is to support the load from the structure above it.
Both doors and windows are not constructed to structurally withstand loads by themselves.
Lintels are mainly found in masonry or brick structures.
Lastly, do not forget to paint them so they do not rust!
This home did not have any lintels which put extra weight on the windows. 🪟