Volumetric analysis is only possible if you can measure out accurate volumes of liquids. For measuring unlnown or varying amounts, a burette is usually used but for measuring known, repeated amounts it is customary to use a pipette.
More information about the use of pipettes can be found here.
A pipette is usually used for delivering accurately measured amounts of liquid to a reaction vessel, for instance for putting the aliquot of reagent into the flask that is to be titrated.
Volumetric pipettes – have a single measurement and come in a range od sizes, usually between 5 and 25 cm3.
Graduated pipettes – also come in a range of sizes, usually from about 1 to 10 cm3 but they have graduations marked on the side and can thus be used for delivering non-standard volumes.
When filling pipettes, it is customary to use a pump of some sort. In years past, it was common to ‘mouth pipette’ – to suck the liquid up using suction from your mouth, like a straw. For reasons we hope are obvious, this is now not recommended.
