Gases are unique states of matter that offer numerous benefits and applications across many different industries and scientific disciplines. Gases are unique in their ability to consistently expand and fill any volume of space available and, in contrast to liquids and solids, they take up large volumes of space because of the distance between the molecules which make up the gas. On the molecular level, gases are composed of elements and compounds in a combined gaseous form that can travel in any direction, as long as there is room to move. While expandable, gases can be compressed in a container to occupy proportionately less space than when uncaged. This ability to compress and expand allows scientists and engineers to move, store and transport gases through a system of pressurized tanks, pipelines and transport vessels. This makes gases practical in a number of fields, from medical respirators to internal combustion engines and air conditioners. Because gases can also be more easily mixed together than liquids and solids, they offer an enormous amount of potential for chemical reactions and industrial processes. From chemical processing in the laboratory to large-scale fuel transformation in the refinery, gases are the raw material for numerous industries and professions. In addition, speciality gases — such as sulfur hexafluoride and other gaseous mixtures used in analytical chemistry — require extremely specific and complex fundamental components, which are only possible due to the uniqueness of gases. Overall, scientists and engineers from various fields have leveraged the special qualities of gases to benefit a wide range of industries. Gases are able to expand, compress, and mix together, which helps them provide a number of helpful qualities and applications. Without gases, many industrial processes, scientific studies, and everyday applications — a lot of what modern society takes for granted — would not be feasible, making the unique features of these elusive molecules an invaluable asset to science and engineering.