Optical trapping, pioneered by Arthur Ashkin in the 1970s, has evolved from simple manipulation of particles to precise measurement of nanometer-level displacements and picoNewton-level forces. This review discusses recent advancements in optical trapping, including instrument design, position detection, and calibration. It highlights innovative configurations and applications, such as studying molecular motors, colloidal physics, and polymer mechanics. The review emphasizes the importance of technological developments, like 3D piezoelectric stages with capacitive sensors, which enhance spatial precision and calibration. It also covers theoretical progress in understanding 3D position detection and optical forces on particles of various sizes. The principles of optical trapping involve focusing a laser beam with a high NA objective to generate optical forces, including scattering and gradient forces. The balance between these forces determines the stability of the trap. The review discusses the design considerations for optical trapping systems, including the choice of trapping laser, microscope, objective, and position detection methods. It highlights the importance of laser wavelength, power stability, and the use of high NA objectives for efficient trapping. Position detection methods, such as video-based, imaging, and laser-based techniques, are described, along with their limitations and advantages. The review also addresses dynamic position control, using scanning mirrors, acousto-optic deflectors, and electro-optic deflectors to adjust trap position and stiffness. The choice of laser and detector depends on factors such as cost, power, and wavelength, with considerations for biological applications. The review concludes with the importance of calibration and the ongoing development of optical trapping for both fundamental and applied research.Optical trapping, pioneered by Arthur Ashkin in the 1970s, has evolved from simple manipulation of particles to precise measurement of nanometer-level displacements and picoNewton-level forces. This review discusses recent advancements in optical trapping, including instrument design, position detection, and calibration. It highlights innovative configurations and applications, such as studying molecular motors, colloidal physics, and polymer mechanics. The review emphasizes the importance of technological developments, like 3D piezoelectric stages with capacitive sensors, which enhance spatial precision and calibration. It also covers theoretical progress in understanding 3D position detection and optical forces on particles of various sizes. The principles of optical trapping involve focusing a laser beam with a high NA objective to generate optical forces, including scattering and gradient forces. The balance between these forces determines the stability of the trap. The review discusses the design considerations for optical trapping systems, including the choice of trapping laser, microscope, objective, and position detection methods. It highlights the importance of laser wavelength, power stability, and the use of high NA objectives for efficient trapping. Position detection methods, such as video-based, imaging, and laser-based techniques, are described, along with their limitations and advantages. The review also addresses dynamic position control, using scanning mirrors, acousto-optic deflectors, and electro-optic deflectors to adjust trap position and stiffness. The choice of laser and detector depends on factors such as cost, power, and wavelength, with considerations for biological applications. The review concludes with the importance of calibration and the ongoing development of optical trapping for both fundamental and applied research.