A header course refers to a row of bricks laid in a masonry wall with their short ends, or headers, facing outward. In other words, the narrow end of each brick is visible on the face of the wall. Header courses are typically used for decorative purposes or to create visual interest in brickwork, rather than for structural support.

Header courses are often interspersed with stretcher courses, which consist of bricks laid lengthwise with their long faces, or stretchers, parallel to the face of the wall. This alternating pattern of header and stretcher courses is known as English bond, a traditional bricklaying technique that provides both strength and visual appeal to the wall.

In addition to their decorative function, header courses may also serve practical purposes in masonry construction. For example, header courses can be used to reinforce corners or edges of walls, create decorative patterns or accents, or provide additional bonding between intersecting walls or structural elements.

Overall, a header course adds architectural interest and character to masonry walls while contributing to their structural integrity and stability.