Archaea is a group of microorganisms described by Carl Woese in 1977. Although Archaea have a similar cellular organization to bacteria, their cell wall and cell membrane are quite unique. Archaeal cell wall lacks peptidoglican and cell membrane is composed of ether-lipids which are far more stable than bacteria-specific esther-lipids. Besides, Archaea have some specific external structures, like: archaella, pili, hami and cannulae but their exact functions are still unclear. Most of Archaea obtain energy via anaerobic processes of simple inorganic or organic compounds, however some of these organisms are also able to generate methane in the process known as methanogesis. They reproduce by cell division or budding-like process and some studies demonstrated the mechanisms of genetic transfer such as conjugation, transduction and natural transformation for the Archaea. They are capable of forming biofilms also in interaction with bacteria. Some archaeons, such as Haloferax mediterranei and Sulfolobus islandicus can synthesize antimicrobial agents which are called archaeocins. In recent years huge progress has been made in understanding of Archaea but many aspects of their biology remain still unknown. In this review, we present recent advances in Archaea biology focusing mainly on archaeal morphology, metabolism and reproduction.