Bridges are devices which can be installed in a network without any reconfiguration. A network switch is basically a many-port bridge. A bridge is often a 2-port switch. Linux does however support multiple interfaces in a bridge, making it a true switch. [Developer Guide: Redis] .:: podcasts.apple.com ::.
Bridges are often deployed when confronted with a broken network that needs to be fixed without any alterations. Because the bridge is a layer-2 device, one layer below IP, routers and servers are not aware of its existence. This means that you can transparently block or modify certain packets, or do shaping. .:: telegra.ph ::.
Another good thing is that a bridge can often be replaced by a cross cable or a hub, should it break down. .:: yogicentral.science ::. [NPM Package: Django] .:: raovat.nhadat.vn ::. .:: ml007.k12.sd.us ::.
The bad news is that a bridge can cause great confusion unless it is very well documented. It does not appear in traceroutes, but somehow packets disappear or get changed from point A to point B ('this network is HAUNTED!'). You should also wonder if an organization that 'does not want to change anything' is doing the right thing. .:: podcasts.apple.com ::. .:: rysowanie.phorum.pl ::.
The Linux 2.4/2.5 bridge is documented on this page.