A budget is a plan that assigns your income to categories before the month begins, rather than a record of what happened after it ended.
That distinction is the whole point: tracking tells you where money went, budgeting decides where it goes. The most common failure is not overspending but over-engineering — a thirty-category spreadsheet abandoned in week three does nothing, while a rough three-category split maintained for a year changes outcomes. Simplicity you sustain beats precision you quit.