<p>This article provides an overview of micromilling operation with a focus on the tool wear and discusses prediction models, monitoring techniques, wear mechanisms, measurement methods, and evaluation approaches used to analyze or predict tool wear within the last two decades. In its conclusion, the article highlights future trends and research gaps in the field of micromilling, focusing on tool wear. Based on available literature, it is noted that researchers are exploring substitutes for traditional wear monitoring in micromilling, including optical non-contact apparatus, machine vision systems, and spindle acceleration monitoring or force-vibration analysis systems. Most studies have focused on modeling and prediction of tool wear during the machining operations, with flank wear and edge radius being the most measured outputs in micromilling studies involving tool wear. Overall, the article highlights the need for further research in various aspects related to tool wear of micromilling operations, since tool wear significantly affects machining efficiency, surface quality, cutting forces, and energy consumption. Effective monitoring and prediction of tool wear are essential for performing high-quality and sustainable micromachining operations.</p>