the fastest jet in the world is the Lockheed SR-71 Blackbird. However, it's important to note that the SR-71 has been retired from active service since 1998.
The SR-71 Blackbird was an advanced long-range reconnaissance aircraft developed by the United States during the Cold War. It had a maximum speed of approximately Mach 3.3, which is around 2,193 mph or 3,529 km/h. It could sustain speeds above Mach 3 for extended periods of time.
In terms of speed, the SR-71 Blackbird was an exceptional aircraft and held the record as the fastest jet for many years. However, it's worth mentioning that there are other jets, such as the MiG-25 Foxbat and the NASA X-43, that have reached or exceeded similar speeds.
It's also important to note that military advancements and classified aircraft development may have led to the creation of even faster jets since my last knowledge update. Therefore, there might be more recent developments or prototypes that have surpassed the SR-71 Blackbird's top speed.