A module is handler (plugin) to the apache server
They are in the modules directory and can be loaded with the LoadModule command in the conf file.
Example:
LoadModule rewrite_module modules/mod_rewrite.so
LoadModule headers_module modules/mod_headers.so
To list all modules, execute the following httpd command
httpd -M
Example of output:
Loaded Modules:
core_module (static)
win32_module (static)
mpm_winnt_module (static)
http_module (static)
so_module (static)
actions_module (shared)
alias_module (shared)
allowmethods_module (shared)
asis_module (shared)
auth_basic_module (shared)
authn_core_module (shared)
authn_file_module (shared)
authz_core_module (shared)
authz_groupfile_module (shared)
authz_host_module (shared)
authz_user_module (shared)
autoindex_module (shared)
cgi_module (shared)
dir_module (shared)
env_module (shared)
include_module (shared)
isapi_module (shared)
log_config_module (shared)
mime_module (shared)
negotiation_module (shared)
setenvif_module (shared)
rewrite_module (shared)
php7_module (shared)