This paper introduces a new nonlocal van der Waals density functional, VV10, which is simpler and more accurate than previous nonlocal correlation functionals. The functional is based on the electron density and does not require explicit orbital dependence. It is designed to accurately describe the entire range of dispersion interactions, including both weakly-bound and covalently bonded systems. The functional is computationally efficient and can be implemented in self-consistent calculations. When combined with an appropriate exchange functional, it provides accurate interaction energies and equilibrium intermonomer separations for van der Waals complexes. It also gives accurate covalent bond lengths and atomization energies. The new functional is derived without a full derivation, but it recovers all relevant limits and satisfies exact constraints. The functional is implemented in a Gaussian basis set code and is computationally less expensive than previous nonlocal functionals. The paper also compares VV10 with another nonlocal functional, vdW-DF2, and shows that VV10 performs better in many cases. The results demonstrate that VV10 is a broadly applicable and accurate electronic structure tool for weakly-bound and covalently bonded systems.This paper introduces a new nonlocal van der Waals density functional, VV10, which is simpler and more accurate than previous nonlocal correlation functionals. The functional is based on the electron density and does not require explicit orbital dependence. It is designed to accurately describe the entire range of dispersion interactions, including both weakly-bound and covalently bonded systems. The functional is computationally efficient and can be implemented in self-consistent calculations. When combined with an appropriate exchange functional, it provides accurate interaction energies and equilibrium intermonomer separations for van der Waals complexes. It also gives accurate covalent bond lengths and atomization energies. The new functional is derived without a full derivation, but it recovers all relevant limits and satisfies exact constraints. The functional is implemented in a Gaussian basis set code and is computationally less expensive than previous nonlocal functionals. The paper also compares VV10 with another nonlocal functional, vdW-DF2, and shows that VV10 performs better in many cases. The results demonstrate that VV10 is a broadly applicable and accurate electronic structure tool for weakly-bound and covalently bonded systems.