Denis Howe defined 'sandbox' (Free On-line Dictionary of Computing - FOLDOC, 1993) as a 'Common term for the R&D department at many software and computer companies (where hackers in commercial environments are likely to be found). Half-derisive, but reflects the truth that research is a form of creative play.'
Today, 'sandbox' is more likely to refer to the code technology that provides the basis of Java's security. 'Trusted' code is allowed full access to the system. 'Untrusted' code is restricted to the sandbox, a protected and limited area of memory in which the code may 'play' without causing any damage to the host system. In practice, this usually means that a Java application has full access to the system, while a Java applet (as downloaded from the Internet) is limited to the protected sandbox.