Research for developing price forecasting tools in deregulated markets is at an intermediate stage. Researchers have developed various forecasting models covering most of the deregulated markets. The researchers have paid more attention towards price forecasting in day-ahead electricity markets as compared to real-time electricity markets; whereas, price forecasting in real time electricity markets is difficult as compared to day-ahead electricity markets. Short term price forecasting (STPF) is a complex task because price series is highly volatile with non-constant mean and variance, which is due to non-storable nature and stiff condition of maintaining real time balance of demand and supply of electricity. Considering these points, this work addresses two main issues: first, it discusses the state of the art in short term price forecasting (STPF) and provides an overview of the available literature on STPF models and explain various key issues while developing a price forecasting model; and secondly, it performs an assessment, detailed comparison and evaluation of the forecasting performance of various linear and non-linear models in real time single settlement markets.