<p>Electrical discharge machining (EDM) is a prominent unconventional manufacturing technique used for machining difficult-to-cut conductive materials, offering advantages such as the ability to process materials of varying strength or hardness and the absence of macro forces. However, the presence of bubbles and debris generated within the small discharge gap profoundly influences every aspect of the EDM process. Despite the immense potential of EDM, the intricate mechanisms underlying its technology remain incompletely understood, primarily due to the short processing time and small machining space, making it difficult to accurately describe the gap phenomenon. This paper presents a comprehensive overview of the effects of bubbles and debris in EDM, covering their formation, impact on discharge breakdown, movement within the machining gap, and electrode-based improvements to enhance debris removal performance. Development trends and new directions are also discussed.</p>