Prior to their application in medicine, nanoparticles must be biocompatible and non-toxic. Because they are so small, nanoparticles can enter the body fast and go through a number of different pathways to reach the organs that are intended to be their targets. A range of parameters, including as size, charge, shape, chemistry, and modifications, might influence a nanoparticle's cytotoxicity. In order to assess the toxicity of nanoparticles, this article provides a succinct overview of many in vitro cytotoxicity experiments. Nanoparticle cytotoxicity is a result of their higher surface area to volume ratio. Increased oxidative stress, cellular dysfunction, and ultimately cell death could result from this increased surface area to volume ratio. A wide variety of nanoparticles are covered in this review, including those that are most frequently utilized in biological research as well as those composed of metal and carbon.