The Batcave is Batman’s command center for his war against the criminal underworld of Gotham City. The Batcave is powered by a Hydrogen Generator, allowing its power source to be completely off the grid. The batcave has a supercomputer in it that is more powerful than even the computer systems used by national intelligence agencies(in the Pre-Catacylsm blueprints of the Batcave, it was stated that the Batcomputer was a Quantum-Computer). The batcomputer allows Batman to have around the clock global surveillance and information on all of Bruce’s enemies and allies. The Batcave is linked up to many Wayne Enterprises satellites and is also linked to Oracle allowing her to monitor the cave's security systems.
There are three items that are in every incarnation of the Batcave: a full size Tyrannosaurus Rex in which Batman gained when he was on an adventure in Dinosaur Land, the giant size U.S. Penny was taken as a trophy when he defeated the Penny Plunderer (later retconned to have come from Two-Face instead), and a Giant Joker Playing Card. Batman has a trophy case of all the previous Bat-Suit incarnations. Jason Todd's Robin Uniform costume was put on display after his death in “Death in the Family," Barbara Gordon’s Batgirl costume was also put behind glass after she was forcibly retired by the Joker in "The Killing Joke."
There are also many different secret entrances and exits. One of the most used entrances is behind a grandfather clock, in which he turns the dials to 10:47, which was the time of his parents murder, and it would open the door. A waterfall or camouflaged door is used for connecting to the road for the Batmobile. Also almost anyone who knows who Bruce really is knows how to enter and exit the cave safely.
Several other caves were set up throughout Gotham to accommodate Batman's needs.
The Central Batcave
Located fifty feet below the bottom of Robinson Park Reservoir, is accessible through a secret entrance at the foot of one of the Twelve Caesar statues at the north end of the park. This safe house was put out of commission by Poison Ivy, her "Feraks," and Clayface.
The Batcave South
It is a boiler room of a derelict shipping yard on the docks across from Paris Island. This safe house is accessible through a number of false manholes planted throughout Old Gotham streets.
The Batcave South-Central
Is located in the Old Gotham prototype subway station, a four-block stretch of track sealed in 1896 and forgotten.
The Northwest Batcave
Is a safe house located in the sub-basement of Arkham Asylum. Batman secretly stocked it with emergency rations, all-terrain vehicles, and battery-powered communication equipment.
Is an abandoned oil refinery owned by Wayne Enterprises. It fell out of use during a gasoline crisis when the company moved all its holdings offshore decades ago.
The Los Angeles Batcave
Was used as a headquarters by the Outsiders when Batman rejoined the group. Another was introduced in 2002's Fugitive story arc, this time in the form of an abandoned submarine.
Under the penthouse of the Wayne Foundation building, there is a secret bunker. As of Batman #687, Dick Grayson has taken to using this as his Batcave, stating that he wishes to embody the role of Batman in a way that is specific to him as well as getting closer to the action in the city. The bunker is as well-equipped as the original Batcave, including the Subway Rocket vehicle stationed beneath the bunker.
Bruce created an Arkham Bat-cave when he found a secret location in Arkham Asylum called "Dead-Man's Point." This was where criminals came to commit suicide. Batman jumps off and bat-glides to this location from 100 feet up. An armored Bat-suit, batgrapple and bat bombs are examples of what is stored here.
There are also various secured penthouses scattered across Gotham City, as well as both across the country and around the world. Each has some form of emergency lock down and comes equipped with gadgets, vehicles, rations and medical supplies.
This was the very first version that was detailed and included areas which batman needed to fight crime in the modern day. Batman's aerial vehicles were housed in a mountain, and the Batcave included a workshop where Batman developed new technology to fight his enemies.
The cave contains a crime lab (which is compromised of a DNA spectrograph and electron microscope), a gym (where Batman works out at daily to keep up his physique), a shooting range (since Batman is a master of all firearms), a training facility, and a library. The batcave also contains a bat-costume vault where Batman works on his batsuit and utility belt, a ramp where his batmobile drives off of (his batmobile exists on a hydraulic turntable), a hangar for his batplane and batjet, a mooring where he houses his batboat, and a subway rocket inside the Batcave when it was used for Jean Paul Valley subbing for Batman.
After the events of Cataclysm the batcave received a major redesign and was built not only to be earthquake proof but serve as a bomb shelter and panic room. Batman added more room and made the entire cave operate on different levels to more efficiently use limited space.
In the 2011 DC major relaunch, the batcave received a major redesign. It now contains several batmobiles, an airplane hanger for batman's batplane and batjet, a workshop, digital library, and a host of other equipment.