What is c4?

C4 refers to several things, so to give you relevant information, I need some context. Are you referring to:

• C4 explosives? This is a family of plastic explosives, often used in military and demolition applications. They are known for their relatively high power and ease of handling compared to other explosives. Key features include their plasticity (can be molded into various shapes), sensitivity (requiring a detonator), and brisance (shattering power). Specific examples include Composition C4 and Semtex. Information on these is often restricted due to security concerns.

• C4ISR? This stands for Command, Control, Communications, Computers, Intelligence, Surveillance, and Reconnaissance. It's a term used in military and defense contexts to describe the integrated systems and processes used for gathering and acting on information.

• C4 architecture? In software engineering and systems design, C4 is a model-based approach for visualizing software architecture. It uses four levels of diagrams – context, container, component, and code – to represent the system from a high-level overview to its implementation details. This is a popular method for improving communication and understanding within development teams.

• Something else? If none of the above apply, please clarify what "C4" refers to in your question.

Please specify which C4 you're interested in to get a more precise and helpful answer.