Coating

A coating located on a surface of a substrate, comprising:

• one or more layers,
• at least one of the layers being a domain structure layer constituted of two or more domains different in composition and a thin layer different in composition from each of the domains,
• the thin layer being located between any one domain and any another domain and in contact with the domains,
• a first domain which is one of the two or more domains and a second domain which is another one of the two or more domains, each of the first domain and the second domain being composed of at least one element selected from the group consisting of Al, B, Si, and elements of group 4, 5, 6 in the periodic table and at least one element selected from the group consisting of B, O, C, and N,
• the thin layer being composed of at least one element selected from B and Si and at least one element selected from B, O, C, and N,
• a plurality of the first domains being present in the domain structure layer,
• when a size of each first domain in an in-plane direction of the domain structure layer is defined as a diameter of a virtual circumcircle in contact with the each first domain, an average value of the size of the each first domain being not smaller than 1 nm and not greater than 10 nm, and
• a thickness of the thin layer in a direction of thickness of the domain structure layer being not less than 1 atomic layer and not more than 10 atomic layers.