What do we know about DNA mechanics so far?

•DNA molecules are often bent, twisted, and stretched.•DNA mechanics has been studied using many theoretical models.•DNA mechanics crucially depends on physiological conditions.•DNA exists in overstretched conformations under applied forces.•DNA mechanics is the key input for the DNA nanotechnology. The DNA molecule, apart from carrying the genetic information, plays a crucial role in a variety of biological processes and finds applications in drug design, nanotechnology and nanoelectronics. The molecule undergoes significant structural transitions under the influence of forces due to physiological and non-physiological environments. Here, we summarize the insights gained from simulations and single-molecule experiments on the structural transitions and mechanics of DNA under force, as well as its elastic properties, in various environmental conditions, and discuss appealing future directions.