An electrical enclosure is a cabinet for electronic equipment, used to mount components and protect contents from the surrounding environment. Enclosures come in all shapes and sizes, with many different specifications that provide different degrees of protection.
In most cost cases, enclosures are differentiated first by their NEMA rating (or IP rating for IEC member countries). NEMA enclosure types vary from general purpose to weather-resistant to watertight to submersible, with varying degrees of protection between each standard. Enclosures can even be rated for use in hazardous environments, resistant to explosions or hazardous materials.
Modern electrical enclosures are composed of rigid metals like stainless steel and aluminum, or plastics like fiberglass and polycarbonate. They are highly customizable - including which back and side panels are used, which door is included, and much more - to fit the end use application as necessary.