Vacutainers are sterile, single-use, evacuated blood collection tubes used for the collection, transport, and processing of venous blood specimens for laboratory diagnostics. Each tube contains a pre-measured vacuum that draws a precise volume of blood and, in most tubes, a specific additive (anticoagulant, clot activator, preservative, separation gel, or culture media) that preserves specimen integrity for the required analysis. International color-coding of tube closures (e.g., lavender-EDTA, light blue-citrate, gold-serum separator) enables immediate identification of additive and intended use. Available in glass or shatter-resistant PET plastic, with draw volumes ranging from 2 mL to 10 mL. Strict adherence to the CLSI-recommended order of draw, complete fill volume, gentle mixing, and immediate centrifugation are essential for specimen quality and accurate test results. An indispensable device in modern laboratory medicine, clinical practice, and blood banking.