In this talk, a review of the advances made in the past twenty-five years in sensor array and multichannel signal processing (SAM) is first presented. As it is not possible to give an exhaustive list for all of them, we will focus on five major topics and introduce the corresponding progresses made in tackling their respective technical challenges: beamforming (including robust adaptive beamforming and frequency invariant beamforming), direction of arrival (DOA) estimation (including sparsity based and underdetermined DOA estimation), sensor location optimization, target/source localization based on sensor arrays, and multiple-input-multiple-output (MIMO) arrays (including MIMO radar and MIMO for wireless communications). The first two are classic SAM topics from the very beginning of SAM research, while the latter three were only studied systematically in the past decades. Then, six new developments in the SAM area are introduced to give an indication about possible future research directions, including graph signal processing for sensor networks, tensor-based array signal processing, quaternion valued array signal processing, one-bit and non-coherent sensor array signal processing, machine learning and artificial intelligence for sensor arrays, and array signal processing for next-generation communication systems.