The paper discusses the implications of recent neutrino oscillation data from the SNO solar neutrino experiment and the K2K long-baseline neutrino experiment for the lepton mixing matrix. The combined data strongly suggest a specific form of the mixing matrix, known as tri-bimaximal mixing, which involves effective bimaximal mixing of $\nu_\mu$ and $\nu_\tau$ at the atmospheric scale and effective tri-maximal mixing of $\nu_e$ with $\nu_\mu$ and $\nu_\tau$ at the solar scale. The authors provide simple mass matrices that lead to tri-bimaximal mixing and discuss its relation to the Fritzsch-Xing democratic ansatz. They emphasize that tri-bimaximal mixing is consistent with the data from both solar and atmospheric neutrino experiments, while other models, such as trimaximal mixing, are ruled out. The paper also explores the implications of tri-bimaximal mixing for future experiments, such as MINOS and KAMLAND, and notes that exact tri-bimaximal mixing would imply no high-energy matter resonance and no intrinsic CP violation in neutrino oscillations.The paper discusses the implications of recent neutrino oscillation data from the SNO solar neutrino experiment and the K2K long-baseline neutrino experiment for the lepton mixing matrix. The combined data strongly suggest a specific form of the mixing matrix, known as tri-bimaximal mixing, which involves effective bimaximal mixing of $\nu_\mu$ and $\nu_\tau$ at the atmospheric scale and effective tri-maximal mixing of $\nu_e$ with $\nu_\mu$ and $\nu_\tau$ at the solar scale. The authors provide simple mass matrices that lead to tri-bimaximal mixing and discuss its relation to the Fritzsch-Xing democratic ansatz. They emphasize that tri-bimaximal mixing is consistent with the data from both solar and atmospheric neutrino experiments, while other models, such as trimaximal mixing, are ruled out. The paper also explores the implications of tri-bimaximal mixing for future experiments, such as MINOS and KAMLAND, and notes that exact tri-bimaximal mixing would imply no high-energy matter resonance and no intrinsic CP violation in neutrino oscillations.