Before deregulation, one company provided all aspects of your electric service: generation, delivery, sales, billing and support. After deregulation, these components are separated. Electricity is now generated in competing power plants all across Texas.
These plants connect to a network called "The Grid." The Grid is managed by the Electric Reliability Council of Texas, or ERCOT. ERCOT oversees the transmission of electricity from the power plants to the population centers.
Once electricity reaches a city, its delivery across wires to your home or business is handled by a single operator. This regulated transmission and delivery provider [TXU Electric Delivery, Centerpoint, AEP Central, AEP North or Texas New Mexico Power] cares for all power lines and responds to any and all outages.
Finally, the marketing of electricity to consumers is handled by Retail Electric Providers, or "REPs". They are licensed by the state and include Ambit Energy and companies like TXU, Reliant, CPL, WTU and First Choice.