Herbicides have different modes of action and are effective for different weed species. Nowadays, genetic modification of crops to create herbicide-tolerant plants is a necessity. The significant progress in molecular genetics has helped us in identifying and transferring herbicide-resistant genes to crop plants. Most herbicide-tolerant plants have been created through genetic engineering. More than 47% of the cultivated area of transgenic crops is dedicated to herbicide-tolerant plants. Perhaps the most important achievement of genetic engineering in agriculture is the production of herbicide-tolerant crops. Various sources of herbicide tolerance have been used to produce herbicide-tolerant crop cultivars, such as genetic diversity in germplasm, random mutagenesis in plants and selection for herbicide tolerance, gene transfer from resistance sources such as bacteria to plants, and alteration of the specific position of an enzyme and genome editing in plants using advances in biotechnology. This article deal with commercial herbicide-tolerant transgenic plants in the world, and explains the mechanism of developing resistance to herbicides.