In the last Editorial, we presented the evolution of the journal "Energy and Thermofluids Engineering, ETE" (Mahbubul 2021) and mentioned that the Journal focuses on three main areas: renewable energy, conventional energy, and thermofluids engineering. The current Editorial is about nanofluids as one of the most promising thermofluids. Nanofluids are complex mixtures of nanoscale solid particles (1-100 nm) with heat transfer fluids. Conventional heat transfer fluids (e.g., water, glycols, refrigerants, oils, etc.) have very low thermal conductivities. This restricts the thermal phenomena, resulting in poor thermal efficiencies and exergetic outputs. When nanofluids are designed to have high thermal conductivity nanoparticles, they exhibit higher thermal conductivities than those of conventional heat transfer fluids.