A budget is the best estimate of future performance over a period of time. A budget is a plan of how you might meet your goals, and gives you a way to measure your actual performance against your plan.
Difference between budget and forecast
A budget focuses mainly on income and expenses in your Profit and Loss Account. A cash flow forecast records all money coming in and going out of your business bank accounts. It includes items you won't find in your profit and loss account, such as buying assets, taking out or repaying a loan, or paying taxes.