Star Trek: 10 Classified Starfleet Secrets
6. Discovery And The Spore Drive
After its sister-ship, the USS Glenn was destroyed, Discovery became Starfleet's only ship equipped with a displacement-activated spore hub drive. This unique technology is the fastest and most advanced method of travel ever seen on screen. The ship can access a universe-wide network of mycelium to instantaneously move across the galaxy.
The tech was highly classified, and was even developed with the involvement of Section 31. Although the Klingons were aware Discovery could appear out of nowhere, they had no idea how the spore drive functioned.
After Discovery and its crew were transported to the future following the battle with the artificial intelligence Control, Spock recommended to Starfleet that Discovery should be reported as destroyed and keep classified all information regarding the spore drive and Control. Clearly they listened to his advice, as Starfleet never used spore drive tech again until Discovery returned in the 32nd century. When they got to the future, the spore drive was instrumental in protecting what remained of the Federation and solving the mystery of The Burn.