An electricity transmission utility is a company or entity responsible for the bulk transfer of high-voltage electrical energy from generating stations to electrical substations. These utilities are the backbone of a country's power grid, operating and maintaining the vast network of towers, overhead lines, and substations that form the "electrical superhighway."

Their main responsibilities include:

1. Grid Operations: Balancing the supply and demand of electricity in real-time to ensure grid stability and prevent blackouts.

2. Maintenance & Reliability: Performing regular inspections, repairs, and upgrades to transmission lines and substations to ensure a consistent and reliable power supply.

3. Infrastructure Development: Planning and executing new projects to expand the transmission network, integrate new power sources (like renewable energy), and meet the growing energy demands of a population.

These companies operate in a highly regulated environment, with a strong focus on safety, efficiency, and reliability.