The start of the documents typically has the HTML5 <header> tag. It is indicated so that the introduction or navigation elements that can be utilized by the user when the web page opens can be accessed easily. Typically, the HTML5 <header> tag is where details like headings, subheadings and version information are placed.
It has to be noted though that HTML5 <header> tag is not supposed to be placed within the <footer>, <address> or within another <header> element.
The HTML5 <header> tag is compatible with the different web browsers that we typically use these days like Firefox, Internet Explorer, Opera, Google Chrome or Safari.
There is no use comparing the functions of HTML5 <header> tag with how it is used in HTML4 since it is newly introduced only for HTML5.
Both the Global Attributes and Even Attributes are compatible with the HTML5 <header> tag.