Security of supply is ensured through the interaction of several links in a chain. There are various different players involved in this chain. Producers of electricity, transporters, distributors and customers are all involved in this process. Each link in this chain must exercise due care in the performance of their assigned role in accordance with market and system rules. The assignment of roles, tasks and responsibilities to the players must be governed by clear and binding legal relationships so that the players can engage in a market-oriented activity. Within this new understanding of roles, the sector clearly makes a substantial contribution towards ensuring security of supply.