A website is a collection of files and/or folders that when requested using a domain name via a web browser such as Internet Explorer, Edge, Chrome or Firefox, will be delivered and displayed in the users web browser, either on their own PC or on their mobile device such as a tablet or a mobile phone.
Websites typically use Domain Names which act like signposts to these files/folders so that when a user types in www.bluebit.co.uk for example, the signposts point the browser to the right location where these files/folders are stored. This location is typically on a web server providing web hosting which is a computer or computers running 24/7/365, waiting for requests for these files.
A website can be responsive. This means that the developer has thought about how the website will look not only on a Windows PC or Apple Mac screen, but also on a mobile device in portrait or landscape mode. This is incredibly important as more than 50% of all surfing and decision making is now carried out on mobile devices.