A single or one page website is simply a website that only contains one HTML page. Content on single page websites is fully loaded in the initial page, making the experience more continuous and fluid for the user. Users click navigation links that allow them jump to destinations on the page, or scroll down the page to reach different sections of content.
Single page websites aim to provide just the right amount of information for a user to make a decision and act on it. This is why single-page design is often used for Landing Pages, portfolios and event-related websites.