After the resistor, capacitor, and inductor comes the memristor. Researchers at HP Labs have discovered a fourth fundamental circuit element that can't be replicated by a combination of the other three. The memristor (short for "memory resistor") is unique because of its ability to, in HP's words, "[retain] a history of the information it has acquired."
HP says the discovery of the memristor paves the way for anything from instant-on computers to systems that can "remember and associate series of events in a manner similar to the way a human brain recognizes patterns." Such brain-like systems would allow for vastly improved facial or biometric recognition, and they could be used to make appliances that "learn from experience."
In PCs, HP foresees memristors being used to make new types of system memory that can store information even after they lose power, unlike today's DRAM. With memristor-based system RAM, PCs would no longer need to go through a boot process to load data from the hard drive into the memory, which would save time and power—especially since users could simply switch off systems instead of leaving them in a "sleep" mode that keeps memory powered. HP says memristor-based RAM could one day replace DRAM altogether.