Of an action, that executes separately from other events or actions. Asynchronous actions are performed in such a way that other actions can be performed simultaneously. For example, in the Query Designer, queries are executed asynchronously. Because individual results are returned as they are found, you can view results or perform other actions while the query continues to search for additional results. back end The server or engine in a database system. In general, back end refers to the system that is the repository for the data, in contrast to the client, which presents data to the user. In a client/server system, the back end is the server. In an integrated database system, such as Microsoft Visual FoxPro or Microsoft Excel, the back end is the core database functionality of the product. As a rule, the back end contains the code that handles not only data storage, but indexes, validation, triggers, referential integrity, and other database functions.