Here is a list of all topics with brief descriptions:

[detail level 12]

Actions
API
Feed
CommentStore
DifferenceEngine
Dump
ExternalStorage
▼File Repository
File abstraction
▼Hooks	Hooks allow custom code to be executed when an event occurs; this module includes all hooks provided by MediaWiki Core; for more information, see https://www.mediawiki.org/wiki/Manual:Hooks
ResourceLoader Hooks
Installer	The Installer helps admins create or upgrade their wiki
JobQueue
▼Internationalisation
Languages
▼File backend
Lock management
Cache
Database	This group deals with database interface functions and query specifics/optimisations
Redis
Media
Pager
Parser
Profiler
▼ResourceLoader
ResourceLoader Hooks
Search
Skins
SpecialPage
Users watchlist handling
Upload related
Entry points
▼Maintenance
Benchmark
Maintenance archives