A burette (also buret) is a vertical cylindrical piece of laboratory glassware with a volumetric graduation on its full length and a precision tap, or stopcock, on the bottom. It is used to dispense known amounts of a liquid reagent in a titration experiment. Burettes are extremely precise: class A burettes are accurate to ± .05mL. This precision makes careful measurement of a burette very important to avoid systematic error. When reading a burette, the viewer's eyes must be at the level of the graduation to avoid parallax error. Even the thickness of the lines printed on the burette matters; the meniscus of the liquid should be touching the top of the line you wish to measure from. A common rule of thumb is to add .02mL if the bottom of the meniscus is touching the bottom of the line. Click here to see a burette. 
External links
http://www.dartmouth.edu/~chemlab/techniques/buret.html