"A brief introduction of theoretical and experimental research activities of spintronics materials, devices and applications recently. Giant Magnetoresistance (GMR) sensors are promising candidates for biomedical and environmental application such as detecting virus, cancer cells or heavy metal atoms. This detecting method is simple and convenient for individuals to diagnose health issues. The chapter will explain why the GMR materials and devices are useful in these specific applications and also involve the post 2016 developments for GMR sensors. TMR has much larger value of magneto-resistance than GMR, which provides higher resolution for detecting magnetic field. Now it is used in magnetic read head, earth magnetic sensors or other magnetic field detection related applications. The very recent progress on TMR sensors and its industry prospect will be also introduced in this chapter. Spin transfer torque (STT) which transfers spin angular momentum to adjacent magnets to manipulate the spin direction, will be applied widely in the next generation non-volatile STT-MRAM. STT-MRAM has the potential to become a leading storage technology, thanks to its high performance, easy downscaling to below 10 nm nodes and low cost. Recent research of STT-MRAM is now focusing on improving the thermal stability, endurance and TMR value, as well as lowering critical switching current"-- Provided by publisher