This article introduces a novel approach for space-time-coding digital metasurfaces, which enable simultaneous control of electromagnetic (EM) waves in both space and frequency domains. The proposed method combines space and time modulation to achieve precise control over the propagation direction and harmonic power distribution of EM waves. The study demonstrates the application of this technique in harmonic beam steering, beam shaping, and scattering-signature control. A prototype metasurface, controlled by a field-programmable gate array (FPGA), is fabricated and tested, showing good agreement between numerical and experimental results. The metasurface uses a space-time coding sequence to optimize harmonic beam steering, achieving significant improvements in scattering power and beam direction control. The research builds on the development of digital coding metasurfaces, which allow for programmable control of EM waves through discrete phase or amplitude states. These metasurfaces have been applied in various fields, including wireless communications, cognitive radars, and holographic imaging. The proposed space-time-coding metasurfaces extend this concept by incorporating time modulation, enabling more flexible and precise control over EM wave manipulation. This approach allows for the generation of vortex beams, reprogrammable holograms, and other complex wave patterns. The study also addresses the challenge of reducing radar cross-section (RCS) by redistributing scattered power in both space and frequency domains. The proposed metasurfaces achieve this by using time-modulated coding sequences to suppress backscattered power and spread it across multiple sidebands. The experimental results validate the effectiveness of the proposed approach, demonstrating its potential for applications in wireless communication, radar systems, and other areas requiring precise control of EM waves. The research highlights the versatility of space-time-coding metasurfaces in enabling advanced wave manipulation and control.This article introduces a novel approach for space-time-coding digital metasurfaces, which enable simultaneous control of electromagnetic (EM) waves in both space and frequency domains. The proposed method combines space and time modulation to achieve precise control over the propagation direction and harmonic power distribution of EM waves. The study demonstrates the application of this technique in harmonic beam steering, beam shaping, and scattering-signature control. A prototype metasurface, controlled by a field-programmable gate array (FPGA), is fabricated and tested, showing good agreement between numerical and experimental results. The metasurface uses a space-time coding sequence to optimize harmonic beam steering, achieving significant improvements in scattering power and beam direction control. The research builds on the development of digital coding metasurfaces, which allow for programmable control of EM waves through discrete phase or amplitude states. These metasurfaces have been applied in various fields, including wireless communications, cognitive radars, and holographic imaging. The proposed space-time-coding metasurfaces extend this concept by incorporating time modulation, enabling more flexible and precise control over EM wave manipulation. This approach allows for the generation of vortex beams, reprogrammable holograms, and other complex wave patterns. The study also addresses the challenge of reducing radar cross-section (RCS) by redistributing scattered power in both space and frequency domains. The proposed metasurfaces achieve this by using time-modulated coding sequences to suppress backscattered power and spread it across multiple sidebands. The experimental results validate the effectiveness of the proposed approach, demonstrating its potential for applications in wireless communication, radar systems, and other areas requiring precise control of EM waves. The research highlights the versatility of space-time-coding metasurfaces in enabling advanced wave manipulation and control.