Because web sites are viewed and shared on many differnt devices you cant just create a page that looks great on a desktop computer sceen and expect it to also look great on your mobile device
To make is possible for web sites yo work across a range of devices, web pages use two seperate tools, also called languages. The first tells your device what to display on screen and the second tells your device how to display it.
Hypertext Markup Language (HTML) and Cascading Style Sheets (CSS) are two common tools used to create and present digital media. In the same way that English, Māori and Sign language are official languages of New Zealand that are used to create traditional media, HTML and CSS are two of the official languages of the internet used to create pages and many Apps.
As with any language, digital or not, they change over time and have "offcial" version. The current HTML versionis 5 and CSS is 3.
HTML describe the structure and meaning of your media.It says, "this part is a heading" or "this part is a paragraph" or "this part is a navigation black". CSS is used for presentation. It tells your device how to display the media and can tell differnt devices to display the same media differntly.
For example, take a look at the LearnCoach web site as it appears on a mobile device and on a desktop browser. The information is the same, but using CSS, the presentation is deffernt.
