The electric industry was a regulated monopoly for 70 years handling all parts of electrical provision including: generation, transmission and distribution, and retail.
Before the market opened in 2001, there was: no competition, no consumer choice and no product selection.
With deregulation, some changes were made and some were not. The most important thing however, is that the reliability should stay the same.
The Texas Retail Electricity Market opened to competition in 2001 and provided customers more convenient services. Customers can now choose their own electricity provider (REP) but the choice of REP should not affect the reliability of service.
Transmission and distribution service providers (TDSP) handled the transmission and delivery of electricity. They own and maintain wires and poles, read meters, and restore power outages. TDSPs include Oncor, Centerpoint, AEP-TCC, AEP-TNC and TNMP.