Resumen
In our daily existence, troubled and changing, economy occupies a large space. Increasingly, more economic concepts such as public budget and public expenditures enter within our daily language. Increasingly, we are assailed with data information about the sustainability of expenditure, about how and when budget allows us to make certain expenditures. Thus, an insight into the functional mechanism and a public institutional budget is always a topical issue. About the budget, as a financial and management tool of a public, we can not discuss without reference to economic classifiers public spending. Budget public institution acquires through economic classification of expenditure substance and reality.