Proxy setup feature is also an important feature provided by any browser. This feature allows a user to forward the requests made by a browser to an intermediate proxy. Most of the companies use some sort of proxy device to avoid data leakage and those settings can be done in browser to limit or monitor the browsing process. Proxy options are also popularly used by penetration testers to capture the request and responses sent and received by a browser. They generally use some interception proxy tool and configure the settings in browser. In day-to-day life also proxy setup can be used for anonymous browsing or browsing or visiting some pages that are country restricted. In that case a user just has to collect one proxy IP address and the port number of some other country where that site or content is available then setting up the same in a browser to visit those pages.
Proxy setup in Firefox Go to Menu → Options → Advanced → Network → Connection Settings → Manual proxy configuration and add the proxy here.
Proxy setup in Chrome Go to Menu → Settings → Show advanced settings → Under Network click on Change proxy settings → Click on LAN Settings → Check Use a proxy server for your LAN (These settings will not apply to dial-up or VPN connections.) and add your settings.