DISA stands for Defense Information Systems Agency. It is like a really big computer system that helps the United States government and military stay connected with each other. Just like how you can use your own computer or smartphone to send emails or messages to your friends and family, DISA allows the government and military to communicate with each other using special tools and systems. This helps them work together, share important information, and stay safe. Think of it like a really cool secret club where all the members can talk to each other and plan really important things, like how to protect our country!