Definition
Budget
A plan for your money that tells every dollar where to go before the month starts.
A budget is simply a plan that matches the money coming in against the money going out, so you decide where your income goes instead of wondering where it went. It is not about restriction; it is about intention.
A working budget lists your take-home income, your fixed bills, your variable spending, and your savings, and makes sure they add up to your income and no more. The method you use to build it (the 50/30/20 rule, a zero-based budget, or cash envelopes) matters less than actually having one and checking it.