Official docs outline
7 sections- OpenMP specifications
Official OpenMP API specification versions covering parallel regions, worksharing, tasking and target offload.
- OpenMP 5.2 specification PDF
Directives, clauses, tasking and device offload semantics.
- libgomp manual
GCC's OpenMP runtime library including directives support, runtime routines and environment variables.
- Runtime library routines
omp_get_num_threads, omp_set_num_threads and locks.
- Environment variables
OMP_NUM_THREADS, OMP_SCHEDULE and OMP_PROC_BIND.
- LLVM OpenMP
The LLVM OpenMP runtime libomp and libomptarget offloading to GPUs.
- OpenMP reference guide
Quick reference cards for directive and clause syntax in C, C++ and Fortran.
Each section links to the official page. Titles and summaries by Extra Credit; the docs belong to their authors.