All this data is potentially out of date, and should be taken with a truckload of salt
A jump bridge is a static emplacement that allows a ship to move great distances, without the assistance of anyone else online. These are commonly put into networks, allowing a ship to move up to their 0.0 home quickly.
Jump bridges are set up by player alliances at their POS' in their sovereign space. The placing of these bridges link distant systems in a similar fashion to a stargate. One of the main differences is that the jump bridge uses liquid ozone to fuel the bridge for the jump.
By placing these structures, alliances create a highway system that allows very fast travel through 0.0 space. They are a time saver of immense proportions, and allow for the players to have more access to their home systems deep in 0.0
Jump bridges also facilitate the quick response ability to alliances when attacked. traditionally a system may be 30 jumps from your home system. If you were attacked there, it would take you 30 jumps X (X number of minutes per jump) to get to your destination. With jump bridges, a system 30 jumps away may only be 3 using the jump bridge technology.
PVP: if you are warp disrupted by another player you can not jump through a jump bridge.