The HTML <base> element specifies the base URL to use for all relative URLs contained within a document. There can be only one <base> element in a document. 
The HTML <head> element provides general information (metadata) about the document, including its title and links to its scripts and style sheets.
The HTML <style> element contains style information for a document, or part of a document. By default, the style instructions written inside that element are expected to be CSS.
The HTML <title> element defines the title of the document, shown in a browser's title bar or on the page's tab. It can only contain text, and any contained tags are ignored.
The HTML <link> element specifies relationships between the current document and an external resource. Possible uses for this element include defining a relational framework for navigation. This Element is most used to link to style sheets.
The HTML <meta> element represents any metadata information that cannot be represented by one of the other HTML meta-related elements (<base>, <link>, <script>, <style> or <title>).