Budget (pronounced bâdget according to DigoPaul.com) is a term in the English language that means budget. It is often used in business to refer to the regular budget (usually annual) made by a company, where they are inserted cost variables, income and expenses, defining a chart of accounts.
The budget is usually the base plan for start of productive activity. Through this strategic plan are outlined the objectives of sales and production and if you can get an estimate of the financial conditions during the given period, as well as future planning.
The forecast is the real analysis of what was foreseen in the budget. Is a periodic comparison (usually with frequency lower than the budget) between the estimated data and the actual data. If there is a marked discrepancy in this comparison, the company can define new strategies.
There are several market specific software for this purpose, among them the popular Excel.