What is certified seed and how is it different from saved seed?

Certified seed is produced under a recognised seed certification scheme and carries a tag (commonly blue/azure for certified) guaranteeing minimum genetic purity, physical purity, and germination percentage, so you get uniform, vigorous, true-to-type plants. Farmer-saved seed can be fine for self-pollinated crops for a few seasons but loses vigour and purity over time and cannot be used for hybrids, which must be bought fresh each season. Following the recommended seed replacement rate (replacing part of your seed with fresh certified seed periodically) keeps yields up. Always check the tag, lot number, germination percentage, and validity date, and keep the bill and a sample.