This document describes a project that analyzes retail chain sales data and forecasts future sales. The goal is to help Walmart store managers monitor weekly sales for different departments. The analysis examines factors like markdown effects, fuel costs, temperature, unemployment, consumer price index, etc. and their impact on sales using simple and multiple linear regression models. Different time series forecasting algorithms are applied like seasonal naive, time series linear model, ARIMA, STL with ETS and ARIMA. The best algorithm is selected as STL-ARIMA based on the lowest MAE (mean absolute error) and its residual plot showing white noise residuals, though it takes more time than some other models. The project aims to provide