The Korean traditional Giwa known as the giwa (瓦, roof tile) is an essential component of a building that was made by molding fine clay and baking it in high temperature in a kiln. The Chinese character “wa” 瓦, a logogram representing a roof covering, initially referred to earthenware vessels but its meaning gradually changed to signify the ceramic tiles that were used to cover the roof of a wooden building. Experts believe that the form or shape of the character meaning “roof tile” was made to depict the shape of a curved earthenware utensil overlapped with a pair of tiles.
--- 「Chapter 1. Introduction to Giwa」중에서

Archaeological evidence shows that Goguryeo (37 BCE - 668), one of the three ancient kingdoms that once dominated the Korean peninsula, began to use Giwa sometime between the second and third century, playing a leading role in the development of Giwa in Korea. The tiles of Goguryeo discovered thus far exhibit a remarkable diversity, encompassing ornamental roof-end and ridge-end roof tiles, some with inscriptions, as well as plain convex and concave tiles. The tiles unearthed mainly at the sites of Goguryeo tombs at Gungnaeseong Fortress in present-day Jian and Pyeongyang, the capitals of early and late Goguryeo, also show that the Goguryeo tile makers preferred cloud and lotus motifs in particular to decorate the tiles used to finish the edges of a tiled roof.
--- 「Chapter 2. Giwa in Korean History」중에서

The system of roof tile production refers to the generalized production, supply, and laying of Giwa under a production system based around the royal kilns, which were managed by the dynasty or the state. In principle, the production of Giwa should be determined by the principle of supply and demand; however, the government and a tile making organization regulated it to some extent. During the Joseon Dynasty, the system of roof tile production was organized by organizations responsible for making Giwa, which included the jowaso (roof tile factory) and wagong (roof tile maker).
--- 「Chapter 3. Production of Giwa」중에서

The first stage of Giwa making involves finding and gathering fine-quality clay, and then mixing it with sandy soil to make a refined clay that is ready to use. The clay is then mixed with water and kneaded by the tile maker and his assistant(s), although in the Joseon period the work was sometimes conducted by an ox.