This review updates the progress in thermoelectrics over the past two years, focusing on advancements in charge and heat carrier transport, strategies to enhance the thermoelectric figure of merit (ZT), and discussions on device physics and applications. Key areas of progress include: 1. **Phonon Transport**: Significant advancements have been made in understanding phonon transport in bulk materials through first-principles calculations and experimental tools. Challenges remain in understanding phonon transport across interfaces and in nanostructured materials. 2. **Electron Transport**: Strategies to improve electron transport in thermoelectric materials have been developed, including energy filtering at interfaces and the introduction of resonant impurity levels. However, the understanding of electron transport in complex nanostructures is still evolving. 3. **Device Physics and Applications**: The field is moving towards developing device contacts, module fabrication techniques, and efficiency measurement platforms. New applications, such as solar thermoelectric power generators, are being explored. 4. **Challenges**: Despite progress, challenges remain in understanding phonon and electron transport across interfaces, in developing reliable characterization techniques, and in achieving reproducibility in reported ZT values. 5. **Strategies for the Next Generation of Nanocomposites**: Strategies to enhance ZT include energy filtering at interfaces, the introduction of resonant impurity levels, and the use of nanoparticles. The choice of nanoparticle materials and their integration into host matrices is crucial for effective phonon scattering without significant electron scattering. The review emphasizes the need for more detailed studies of electron transport, the development of standardized characterization techniques, and the integration of advanced theoretical methods to address the remaining challenges in thermoelectrics.This review updates the progress in thermoelectrics over the past two years, focusing on advancements in charge and heat carrier transport, strategies to enhance the thermoelectric figure of merit (ZT), and discussions on device physics and applications. Key areas of progress include: 1. **Phonon Transport**: Significant advancements have been made in understanding phonon transport in bulk materials through first-principles calculations and experimental tools. Challenges remain in understanding phonon transport across interfaces and in nanostructured materials. 2. **Electron Transport**: Strategies to improve electron transport in thermoelectric materials have been developed, including energy filtering at interfaces and the introduction of resonant impurity levels. However, the understanding of electron transport in complex nanostructures is still evolving. 3. **Device Physics and Applications**: The field is moving towards developing device contacts, module fabrication techniques, and efficiency measurement platforms. New applications, such as solar thermoelectric power generators, are being explored. 4. **Challenges**: Despite progress, challenges remain in understanding phonon and electron transport across interfaces, in developing reliable characterization techniques, and in achieving reproducibility in reported ZT values. 5. **Strategies for the Next Generation of Nanocomposites**: Strategies to enhance ZT include energy filtering at interfaces, the introduction of resonant impurity levels, and the use of nanoparticles. The choice of nanoparticle materials and their integration into host matrices is crucial for effective phonon scattering without significant electron scattering. The review emphasizes the need for more detailed studies of electron transport, the development of standardized characterization techniques, and the integration of advanced theoretical methods to address the remaining challenges in thermoelectrics.