I present results from weak gravitational lensing by the large-scale structure from CFHTLenS (Canada-France-Hawaii Lensing Survey). Using multi-band optical data over 155 square degrees, we measure the weak lensing correlation of high-redshift galaxies from small out to very large, linear scales. We reconstruct the largest maps of dark matter ever made, and infer information on cosmological parameters for flat and curved Lamda and dark-energy CDM models, and modified gravity (the latter together with redshift-space distortions from Wiggle-Z). In addition, by comparing the lensing observations with the light distribution from galaxies, we measure the relation (bias and cross-correlation) between total and luminous matter. I will give an introduction to weak gravitational lensing and its use in cosmology. I will present an overview over the CFHTLenS lensing analysis and the likelihood and sampling methods (Population Monte Carlo, PMC). These results will be put in a larger context of large on-going and planned ground- and space-based galaxy surveys such as DES and Euclid.