Complete means the food includes every nutrient a pet needs; balanced means those nutrients exist in proper ratios. A food can be complete but unbalanced if calcium-to-phosphorus ratios are off, for example, which can cause bone problems in growing puppies. The AAFCO statement on the label indicates whether the claim is based on formulation (calculated to meet nutrient profiles) or feeding trials (tested on live animals). Foods for 'all life stages' meet the most demanding profiles (growth and reproduction), while maintenance-only diets suit healthy adults. Toppers, treats, and supplemental foods typically lack this designation and should not be a pet's sole nutrition.