The first pair exports the default tags. The module's manpage normally describes what tags are exported by default. The second pair exports only the tags passed as arguments. The third pair describes the case where the caller does not want any symbols to be imported. See the Exporter manpage for more information.
Exports pollute the namespace of the module user.
Also avoid short or common symbol names to reduce the risk of name clashes. By convention you can use a leading underscore on names to informally indicate that they are internal and not for public use. Download Written by Stas Bekman .