Sap is a fluid transported in xylem cells (vessel elements or tracheids) or phloem sieve tube elements of a plant. These cells transport water and nutrients throughout the plant.
Sap is distinct from latex, resin, or cell sap; it is a separate substance, separately produced, and with different components and functions.
Insect honeydew is called sap, particularly when it falls from trees, but is only the remains of eaten sap and other plant parts.