This chapter mainly summarizes and discusses the LDO application scenarios, control schemes, and future research directions. LDO is suitable for a variety of application scenarios. In different applications, the specifications of LDO have different weights. The three control schemes (analog, digital, switching) of LDO also have their own advantages and applicable scenarios. Analog control excels in handling small current fast transients and scenarios demanding low noise and high power supply rejection (PSR). Digital control is ideal for managing large signals and facilitating process scalability, while switching techniques are optimal for high-current fast transient digital loads. Hybrid control can combine the advantages of different control schemes in certain scenarios. Future research directions include the development of ultralow quiescent current LDOs, low-noise ultrahigh PSR LDOs, scalable fully synthesizable all-digital LDOs, and AI-based automated LDO designs.