SGML Tags are used to define elements in HTML . Different browsers may choose different appearances for the same idiomatic tag. The first word between the angle brackets is the element's name. Some HTML element types allow authors to omit end tags. Some HTML element types have no content.
Element names are always case-insensitive.
Elements are not tags. For instance, the HEAD element is always present, even though both start and end HEAD tags may be missing in the markup. They may appear in any order. Tags are case-insensitive . You can write them in small letters, big letters, or any mixture.