Combine many small pictures together, and use CSS to define background attributes to control the display position and method of the pictures. When the page loads, the entire combined image can be loaded only once, greatly reducing the number of HTTP requests and reducing the pressure on the server. At the same time, the time delay required to load images on hover is shortened, making the effect smoother.
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
