The <head> tag is placed between <html> tag and <body> tag and <head> contains important tags like <title>, <link>, <style>, <base>, <meta>, <script> etc.
The <title> tag defines the title of the HTML document.
<head> <title> Page Title</title> </head>
This tag links External style sheets. External stylesheets are the CSS files(Cascading Style Sheets) which style your HTML document. In laymen terms, CSS makes your website look more attractive and engaging by using style features.