preload

This enumerated attribute is intended to provide a hint to the browser about what the author thinks will lead to the best user experience. It may have one of the following values:
  none: hints that either the author thinks that the user won't need to consult that audio or that the server wants to minimize its traffic; in others terms this hint indicates that the audio should not be cached;
  metadata: hints that though the author thinks that the user won't need to consult that audio, fetching the metadata (e.g. length) is reasonable;
  auto: hints that the user needs have priority; in others terms this hint indicated that, if needed, the whole audio could be downloaded, even if the user is not expected to use it;
  the empty string: which is a synonym of the auto value.

If not set, its default value is browser-defined (i.e. each browser can choose its own default value), though the spec advises it to be set to metadata.

Usage notes:

The autoplay attribute has precedence over this one as if one wants to automatically play a audio, the browser will obviously need to download it. Setting both the autoplay and the preload attributes is allowed by the specification.
The browser is not forced by the specification to follow the value of this attribute; it is a mere hint.
