The HDF5 library has several interfaces, each of which provides the tools required to meet specific aspects of the HDF5 data-handling requirements.

HDF5 C/Fortran Reference Manual (quick links):
Core Library:  H5  H5A  H5D  H5E  H5F  H5G  H5I  H5L  H5O  H5P  H5PL  H5R  H5S  H5T H5VL  H5Z
High Level:   H5LT  H5IM   H5TB  H5PT  H5DS   H5DO  Extensions