The Electric Reliability Council of Texas, Inc. (ERCOT) is an American organization that operates Texas's electrical grid, the Texas Interconnection, which supplies power to more than 25 million Texas customers and represents 90 percent of the state's electric load. ERCOT is the first independent system operator (ISO) in the United States. ERCOT works with the Texas Reliability Entity (TRE), one of six regional entities within the North American Electric Reliability Corporation (NERC) that coordinate to improve reliability of the bulk power grid.

As the ISO for the region, ERCOT dispatches power on an electric grid that connects more than 46,500 miles of transmission lines and more than 610 generation units. ERCOT also performs financial settlements for the competitive wholesale bulk-power market and administers retail switching for 7 million premises in competitive choice areas.

According to an ERCOT report, the major sources of generating capacity in Texas in 2020 were natural gas (51%), wind (24.8%), coal (13.4%), nuclear (4.9%), solar (3.8%), and hydroelectric or biomass-fired units (1.9%).

ERCOT is a membership-based 501(c)(4) nonprofit corporation, and its members include consumers, electric cooperatives, generators, power marketers, retail electric providers, investor-owned electric utilities (transmission and distribution providers), and municipally owned electric utilities.

Power demand in the ERCOT region is typically highest in summer, primarily due to air conditioning use in homes and businesses. The ERCOT region's all-time record peak hour occurred on August 20, 2024, when consumer demand hit 85,931 MW. A megawatt of electricity can power about 200 Texas homes during periods of peak demand. By 2022, ERCOT had 2 GW of grid batteries, with another 6 GW underway.

At the beginning of World War II, several electric utilities in Texas agreed to operate together as the Texas Interconnected System (TIS) to support the war effort. During the war, the grid was interconnected to other states and excess power generation was sent to industries on the Gulf Coast, providing a more reliable supply of electricity for production of metal and other material needed for the war.

Recognizing the reliability advantages of remaining interconnected, TIS members continued to operate and develop the interconnected grid. TIS members adopted official operating guides for their interconnected power system and established two monitoring centers within the control centers of two utilities, one in North Texas and one in South Texas.

In 1970, ERCOT was formed to comply with NERC requirements. However, the Texas grid is not subject to regulation under the Federal Power Act, being an intrastate grid for the purposes of that law. On May 4, 1976, Central Southwest Holdings attempted to force the issue, with an event that was later called the "Midnight Connection", where it connected the grid to Oklahoma for a few hours. This caused lawsuits about whether federal regulation then applied, however the judgement was that this was not sufficient.