What does the numbering system for fertilizers stand for? example: 12-12-12 fertilizer?

that's the level of N/P/K ( nitrogen, phosphorus and potassium)What does the numbering system for fertilizers stand for? example: 12-12-12 fertilizer?
i stay with Chris answerWhat does the numbering system for fertilizers stand for? example: 12-12-12 fertilizer?
The first number is Nitrogen or 'N' the second is Phosphorus or 'P' the third is Potassium or 'K' also known as NPk fertilizers. The number is basically a percentage... meaning if you were to buy 100 pounds of a 12-12-12 fertilizer you would have 12 pounds each of Nitrogen, Phosphorus, and Potassium... Nitrogen is aids leaf production, Phosphorus aids in root production, and potassium everthing in between such as stems