Since HTM files are text-only files, they just contain text (like what you're reading now), as well as text references to other external files (like the image in this article).
Ebe ọ bụ na faịlụ HTM bụ faịlụ naanị ederede , naanị ha nwere ederede (dị ka ihe ị na-agụ ugbu a), yana ederede ederede na faịlụ ndị ọzọ (dị ka onyinyo dị n'isiokwu a).