The article provides a comprehensive review of optical trapping, a technique that has evolved significantly since its inception over 20 years ago. Optical traps are now widely used in both physics and biology, enabling the application of picoNewton-level forces to micron-sized particles with nanometer-level precision. The review covers the development of optical trapping apparatus, including instrument design, position detection schemes, and calibration techniques, with a focus on recent advancements. Key aspects discussed include the principles of optical trapping, the design considerations for optical traps, and the use of piezoelectric stages for precise positioning. The article also explores various methods for position detection, such as video-based, imaging, and laser-based techniques, and the integration of dynamic position control for real-time manipulation of trapped objects. The review concludes with a discussion of innovative optical trapping configurations and their applications.The article provides a comprehensive review of optical trapping, a technique that has evolved significantly since its inception over 20 years ago. Optical traps are now widely used in both physics and biology, enabling the application of picoNewton-level forces to micron-sized particles with nanometer-level precision. The review covers the development of optical trapping apparatus, including instrument design, position detection schemes, and calibration techniques, with a focus on recent advancements. Key aspects discussed include the principles of optical trapping, the design considerations for optical traps, and the use of piezoelectric stages for precise positioning. The article also explores various methods for position detection, such as video-based, imaging, and laser-based techniques, and the integration of dynamic position control for real-time manipulation of trapped objects. The review concludes with a discussion of innovative optical trapping configurations and their applications.