Sandboxing allows you to run a program in a realistic but separated environment. Sandboxing is usually done to either test a program or to analyze a suspicious program that has been detected. Joe and cukoo sandboxes are free sandbox software that you can use as a security analysts and are available in windows, macos, androids, and linux. You can upload any suspicious file and have these two sandbox software provide detailed report on the behavior of the file.
Sandbox is pretty much a controlled environment that monitors the selected item and provides comprehensive report on the selected item. For example, a suspicious email attachment can be opened in a sandbox first. By doing this, it can detect any malicious intent if any. If the attachment tries to connect to any suspicious IP or tries to modify files to unknown extension, it will document this behavior for the report. If no threat is detected, users can choose to open the attachment.