The phrase "touch base" is an idiom that means to make contact with someone briefly, often to exchange information or discuss a matter. It can also refer to checking in with someone to see how they are doing or to review progress on a project or task. The term is often used in a business or professional context, but it can also be used informally in personal conversations. For example, "Let's touch base next week to discuss the details of the project" or "I just wanted to touch base and see how you're doing."