Lazy Loading is a front-end development trick which delays the loading of content below the fold of a page until just before a user scrolls to it. You can think of it as the opposite of image preloading. It ensures that resources, especially those that carry more weight (images, videos, scripts), are only loaded when they have to be.
The biggest advantage of lazy loading your content is that it makes your initial page load quite a bit faster. If the browser doesn’t have to worry about loading in every resource on your page right away, it can load the content immediately visible to a user much quicker. As the user begins to scroll, content will be loaded in.Often, lazy loading is referred to in discussions of infinite scroll. Infinite Scroll is really an alternative to pagination. It is a technique where new content is loaded in every time a user scrolls to the bottom of the page. You’ve probably seen it on the web somewhere, on blogs or sites like Pinterest.
This makes content discovery a lot easier without readers having to click through page after page to find what they are looking for. It also saves you a page load when all you need to do is load in a few more posts for people to view. In the long run, and when implemented properly, lazy loading can make your site a lot faster and can be a really great experience for your users.