The new drug molecule in the world is of minimal value without the convenient delivery system. In fact, development of lipid-based delivery system needs an appropriate selection of excipients, which helps in designing and selecting the invasive and non-invasive routes of delivery. Solid lipid nanoparticles (SLNs) are a substitute for the conventional nano-drugs/colloidal carriers because of higher stabilization of incorporating compounds with excipients. The common ingredients used to formulate SLNs are solid lipid(s), surfactant(s)/co-surfactant(s) or emulsifier(s)/co-emulsifier(s), solvents/co-solvents and active ingredient(s). The absorption of lipid nanoparticles depended on the types and blend of lipids (digestible and non-digestible lipids) used to formulate SLNs. The various categories of surfactants/emulsifiers have been used for the stabilization of solid lipid dispersion. The mixture of emulsifier/surfactant is more effective to exclude particle aggregation. The selection of emulsifiers/surfactants depends on the route of delivery and is more restricted to the parenteral route of administrations. The ionic and nonionic emulsifiers/surfactants with divergent molecular weight have been used to stabilize the colloidal dispersion. The SLNs aggregation can be reduced by addition of cryoprotectants and facilitates to redisperse freeze-dried nanoparticles. These cryoprotectants reduce the crystallization and osmotic activity of water and favor the glassy state of the freezedried sample. In this manuscript, an attempt has been made to over-view the selection of structural components of SLNs such as lipids, surfactants/emulsifiers, solvents/co–solvents cryoprotectors and a suitable drug candidate. This manuscript also highlights the methods of preparation, advantages & disadvantages, invasive & non-invasive routes of delivery and applications of SLNs.