What are various Apache Proxy modules ?

The Apache Proxy Modules

mod_proxy

Core module deals with proxy infrastructure and configuration and managing a proxy request

mod_proxy_http

handles fetching documents with HTTP and HTTPS

mod_proxy_ftp

handles fetching documents with FTP

mod_proxy_connect

handles the CONNECT method for secure (SSL) tunneling

mod_proxy_ajp

handles the AJP protocol for Tomcat and similar backend servers

mod_proxy_balancer

implements clustering and load-balancing over multiple backends

mod_cache, mod_disk_cache, mod_mem_cache

manages a document cache

To enable caching requires mod_cache and one or both of disk_cache and mem_cache.

mod_proxy_html

rewrites HTML links into a proxy's address space.

mod_xml2enc 

supports internationalization (i18n) on behalf of mod_proxy_html and other markup-filtering modules.

mod_headers

modifies HTTP request and response headers.

mod_deflate

negotiates compression with clients and backends