Activity-based costing (ABC) is a costing methodology that assigns overhead costs to products and services based on their actual consumption of activities like production, storage, delivery etc. It was developed in the 1980s as a response to the limitations of traditional costing systems in assigning overhead costs. ABC identifies activities in an organization and assigns the costs of each activity to outputs using cost drivers. It provides more accurate product costs than traditional costing and helps management understand overhead costs better. While it requires more initial costs and maintenance than traditional costing, ABC supports performance management and decision making.