This review provides an overview of the composition and chemistry of Titan's atmosphere, focusing on the vertical profiles of gases at low latitudes. Titan, Saturn's largest moon, has a dense atmosphere primarily composed of molecular nitrogen (N₂) and methane (CH₄), creating a largely anoxic environment. The atmosphere is rich in complex organic molecules, which arise from the breakdown and recombination of simpler species through various chemical processes. The review highlights the importance of Titan's atmosphere in astrobiology, as it shares similarities with early Earth and could inform our understanding of exoplanets. The atmospheric temperature structure is influenced by convection, solar heating, and radiative cooling, resulting in distinct layers such as the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. The vertical profiles of gases like N₂, CH₄, and H₂ are well-mixed, while other gases exhibit decreasing abundance with altitude. The review also discusses the photchemical processes that occur in Titan's atmosphere, including dissociation, ionization, and radical reactions, which lead to the formation of complex molecules. The chemistry of specific molecules, such as hydrogen, methane, acetylene, ethylene, and ethane, is detailed, including their production and loss pathways. For example, methane photolysis leads to the formation of radicals that participate in a chain of reactions, ultimately forming ethane. Acetylene, discovered early in the Cassini mission, is a crucial intermediate in the formation of higher hydrocarbons and is also present on Titan's surface. The review concludes by discussing future research directions, emphasizing the need for further measurements and modeling to understand the vertical profiles of gases and the chemical processes that govern Titan's atmosphere.This review provides an overview of the composition and chemistry of Titan's atmosphere, focusing on the vertical profiles of gases at low latitudes. Titan, Saturn's largest moon, has a dense atmosphere primarily composed of molecular nitrogen (N₂) and methane (CH₄), creating a largely anoxic environment. The atmosphere is rich in complex organic molecules, which arise from the breakdown and recombination of simpler species through various chemical processes. The review highlights the importance of Titan's atmosphere in astrobiology, as it shares similarities with early Earth and could inform our understanding of exoplanets. The atmospheric temperature structure is influenced by convection, solar heating, and radiative cooling, resulting in distinct layers such as the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. The vertical profiles of gases like N₂, CH₄, and H₂ are well-mixed, while other gases exhibit decreasing abundance with altitude. The review also discusses the photchemical processes that occur in Titan's atmosphere, including dissociation, ionization, and radical reactions, which lead to the formation of complex molecules. The chemistry of specific molecules, such as hydrogen, methane, acetylene, ethylene, and ethane, is detailed, including their production and loss pathways. For example, methane photolysis leads to the formation of radicals that participate in a chain of reactions, ultimately forming ethane. Acetylene, discovered early in the Cassini mission, is a crucial intermediate in the formation of higher hydrocarbons and is also present on Titan's surface. The review concludes by discussing future research directions, emphasizing the need for further measurements and modeling to understand the vertical profiles of gases and the chemical processes that govern Titan's atmosphere.