Software for a database or an application related to one or more databases . For specific databases, please use the specific tag (see wiki).
A Database is an organized collection of data, where the latter are usually stored in tables. Those tables can hold relations to each other, to avoid redundancies. For a detailed description, see the linked Wikipedia article.
When to use this tag
If you are looking for database-related software (such as editors, query-builders, or even modules/addons for other applications) which are either cross-database (must support multiple/any database), or you are not yet decided which database it should be, this tag is yours.
When not to use this tag
If the software you are using should be designed for a specific database, you should rather use the specific tag instead (see below). Avoid using both.