ABC analysis is an inventory categorization technique that divides items into three categories (A, B, and C) based on their importance to the business. Category A items are the most valuable, accounting for a significant portion of the overall inventory value but a small percentage of items. Category B items are of moderate value, while Category C items are the least valuable, representing a large number of items but a small share of the inventory value. This method helps businesses prioritize their inventory management efforts and optimize resource planning.