ABC Analysis is a method to categorize inventory items into A, B, and C classes based on their annual monetary value and consumption. A items account for 10-20% of inventory items but 50-60% of spending, and require very strict control. B items are 30-40% of items and 30-40% of spending, requiring moderate control. C items are 40-50% of items but only 5-10% of spending, allowing for loose control. This analysis allows companies to focus control efforts on the most important and costly inventory items.