Direction of Arrival (DOA) estimation is a pivotal aspect of Array Signal Processing (ASP) with significant implications for the performance of modern communication systems. This paper provides a comprehensive review of DOA estimation techniques, encompassing both classical and advanced algorithms. Key methods such as MUSIC, ESPRIT, and their variations as well as Beamforming techniques are analysed for their theoretical foundations, computational complexity, and performance under various conditions. MATLAB simulations are conducted to evaluate the impact of critical parameters such as array element spacing, array geometry, number of snapshots, and signal incidence angle differences on estimation accuracy. Special attention is given to the challenges and enhancements in DOA estimation for MIMO systems, highlighting future directions in adaptive and machine learning-based approaches. The study emphasizes the potential of DOA estimation in applications spanning radar, sonar, wireless communication, and beyond, aiming to bridge gaps between current methodologies and emerging requirements.