DOCTYPE declaration : The DOCTYPE format representing the character format has become much simpler than the existing 4. Existing HTML and XHTML DOCTYPE mainly included the number 4.01 or 1.0 and required complex declarations such as additional reference-related settings. However, starting from version 5, there is no need for complex declarations and no need to set referencing tags.

character encoding : The declaration for character encoding has also become simpler/concise and clearer. Previously, a very long encoding statement declaration was entered, but in HTML5, if you simply set/declare a character set to declare a character encoding, no further steps are required. It may seem bland because not many changes have been made, but since nothing has changed significantly in the basic form, the simplicity has become a very big advantage in the change.