The NHS Digital website contains more background information about HES:
The HES publications focus on headline information about hospital activity. Each annual publication includes a series of national tables and also provider-level breakdowns for some main areas.
All data items included in the published tables are explained in footnotes, and NHS Digital publishes data dictionaries for HES describing the format and possible values for all HES data items:
This data is also readily accessible via an online interrogation service (for NHS users) or via our bespoke extract service: