External Stylesheet is the CSS file that you link from a HTML page using following line of code: <link rel="stylesheet" href="main.css">
Though in MODERN code you should also be using the TYPE and MEDIA attributes -- especially media since what you're sending to screen might not make a lot of sense to print or handheld. <link type="text/css" rel="stylesheet" href="screen.css" media="screen,projection,tv" > Code (markup): The advantages to storing CSS outside the HTML are that you can use the media attribute to target devices by capability so you aren't sending presentation to user agents where it makes no sense, any attributes that are shared across multiple HTML pages are CACHED so you aren't resending the same data over and over again, you can pre-cache the appearance of sub-pages making them appear to load faster for a small penalty on firstload... and in general it keeps the markup cleaner and easier to maintain. Which is why IMHO the STYLE tag should be deprecated altogether, and the STYLE attribute should be used only in the handful of cases where the applied style is being used to convey content... which is very, VERY rare. 99% of the time people use <style> or style="" they're doing it all wrong, and failed to grasp the advantages of semantic markup with separation of presentation from content.
There are 3 ways of declaring a css to your html. 1. Inline (declared within html) 2. Import (getting the source which is not editable through) 3. External (CSS file that is linked externally to your html,mostly used)
linking external style sheet is very easy you have to write this code in the <head>,</head> part <link href="" rel="" type=""> here href stands for hyper refrence i.e name of the style sheet rel stands for relation , you have to type style sheet type stands for the page upon which you had made style sheet