The International Bureau of Weights and Measures () is an intergovernmental organization, one of three such organisations established to maintain the International System of Units (SI) under the terms of the Metre Convention ("Convention du Mètre"). The organisation is usually referred to by its French initialism, BIPM. 

The BIPM reports to the International Committee for Weights and Measures (), which is in turn overseen by periodic meetings of the General Conference on Weights and Measures (). These organizations are also commonly referred to by their French initialisms. 

The BIPM was created on 20 May 1875, following the signing of the Metre Convention, a treaty among 51 nations (). It is based at the Pavillon de Breteuil in Sèvres, France, a site (originally ) granted to the Bureau by the French Government in 1876, where it enjoys extraterritorial status, a status that was clarified by the French decree No 70-820 of 9 September 1970. 

Under the authority of the Metric Convention, the BIPM helps to ensure uniformity of SI weights and measures around the world. It does so through a series of consultative committees, whose members are the national metrology laboratories of the Convention's member states, and through its own laboratory work.
and that is overseen by what?
 the General Conference on Weights and Measures