The major concern for every electrical utility is the ability to provide reliable and uninterrupted service to their customers. Load forecasting is an important component for power system energy management system. Precise load forecasting helps the electric utility to make unit commitment decisions, reduce spinning reserve capacity and schedule device maintenance plan properly. Besides playing a key role in reducing the generation cost, it is also essential to the reliability of power systems. There are three types of load forecasts: short-term, medium-term and long-term. This book focuses on study of short term load forecasting. Long-term demand forecasting presents the first step in planning and developing future generation, transmission and distribution facilities. In this book study of a real sample (Shiraz power distribution network) for forecasting load growth is done, also evaluated various compensation methods from perspectives of long-term load forecasting.