subdomains for the images ,videos and others assets in the web application

what is the benefit from making subdomain for images in my website? is it regarding faster downloading or server caching . I noticed that all big s开发者_如何学Goites like facebook and others are doing something like that for images , videos.....

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It's a common recommendation for high load, high performance websites: Serving images off different servers can improve your overall performance significantly.

Browsers generally only keep 2-5 connections to the same server, so if your webpage has 10 images, the browser will download 2 to 5 of them simultaneously, while the rest waits. Using different subdomains will "trick" the browser, and it will open additional connections, which reduces the overall page load time.

Using a CDN for images, stylesheets and other static content, can also take some load of your webserver, which is another benefit.