The Canada-France-Hawaii Telescope Legacy Survey is a 5-year program carried out jointly by the Canadian and French agencies. It will use the Megaprime/Megacam instrument mounted at prime focus of the 3.6m CFH telescope during the period 2003-2008.

Three surveys will be carried out :

 the "Deep": 4 patchs of 1 square-degree each in u,g,r,i and z, with very long exposure times;
 the "Wide": 4 patchs, 3 of about 7x7 square-degrees each and 1 of about 4x4 square-degrees. All will be observed in u,g,r,i and z, with about 1 hr exposure time per filter;
 the "Very Wide": 1300 patchs of 1 square-degree each in g,r and i, with exposure times of about 5mn.

500 nights will be devoted to the CFHTLS; 200 for the Deep, 170 for the Wide and 130 for the Very Wide.

Scientific goals: Geometry of the universe and dark energy properties (SNIa and cosmic shear; clusters of galaxies); dark matter properties (weak and strong lensing); distant quasars, distant clusters of galaxies, properties of galaxy clustering at high redshift, relation(s) between dark and luminous matters, proper motions of stars in the Galaxy, Trans-Neptunian objects in the Solar System.

Each survey has an Identifier Keyword: [Year][Semester=A/B][L=CFHT ID=Legacy][Survey ID and Priority] :
 03AL01 and 03AL04 denote the Deep survey for period 2003-A and priority A (L01) and B (L03)
 03AL02 and 03AL05 denote the Wide survey for the same period and priority A (L02) and B (L05)
 03AL03 and 03AL06 denote the Very Wide survey for the same period and priority A (L03) and B (L06)