Whats the difference between a Standard Variable Tariff (SVT) and a fixed tariff?

The Standard Variable Tariff (SVT) is a variable energy tariff where the unit rates and standing charges can increase or decrease. The next projected increase of the SVT is the 1st April when the Energy Price Guarantee ends. By signing into a fixed tariff, you lock in your unit rates and standing charges for a certain length of time, normally 12 months. This provides you certainty of the rates you will be paying for the next year, but fixed tariffs are currently higher than the SVT.