Primitives

The foundational types that appear across most subsystems. Read these once and you'll understand a third of the codebase by name.

Primitive	Type	What it represents
Cycle	ngx_cycle_t	The big "world" object — config, listeners, modules
Connection	ngx_connection_t	A network connection (or stream within QUIC)
Request	ngx_http_request_t	One HTTP request (incl. one HTTP/2 or HTTP/3 stream)
Module	ngx_module_t	A static struct that registers everything
Buffer	ngx_buf_t / ngx_chain_t	A span of bytes + its linked-list link
Pool	ngx_pool_t	The bump allocator
String	ngx_str_t	Length-prefixed byte string

Other supporting types that are widely used but covered elsewhere:

• ngx_event_t — see systems/event-loop
• ngx_array_t, ngx_list_t, ngx_queue_t, ngx_hash_t, ngx_rbtree_t, ngx_radix_tree_t — see systems/core
• ngx_log_t — see systems/logging
• ngx_shm_zone_t, ngx_slab_pool_t — see systems/core