authentik consists of a handful of components, most of which are required for a functioning setup.
```mermaid
graph LR
user(User) --> ak_server(authentik Server)
ak_server --> ak_server_core(authentik Server Core)
ak_server --> ak_outpost(Embedded outpost)
ak_server_core --> db(PostgreSQL)
ak_server_core --> cache(Redis)
ak_worker(Background Worker) --> db(PostgreSQL)
ak_worker(Background Worker) --> cache(Redis)
```
### Server
The server container consists of two sub-components, the actual server itself and the embedded outpost. Incoming requests to the server container(s) are routed by a lightweight router to either the _Core_ server or the embedded outpost. This router also handles requests for any static assets such as JavaScript and CSS files.
#### Core
The core sub-component handles most of authentik's logic, such as API requests, flow executions, any kind of SSO requests, etc.
Similar to [other outposts](../outposts/index.mdx), this outpost allows using [Proxy providers](../providers/proxy/index.md) without deploying a separate outpost.
-`/media` is used to store icons and such, but not required, and if not mounted, authentik will allow you to set a URL to icons in place of a file upload
### Background Worker
This container executes background tasks, such as sending emails, the event notification system, and everything you can see on the _System Tasks_ page in the frontend.
#### Persistence
-`/certs` is used for authentik to import external certs, which in most cases shouldn't be used for SAML, but rather if you use authentik without a reverse proxy, this can be used for example for the [Let's Encrypt integration](../core/certificates.md#lets-encrypt)
-`/templates` is used for [custom email templates](../flow/stages/email/index.mdx#custom-templates), and as with the other ones fully optional
### PostgreSQL
authentik uses PostgreSQL to store all of its configuration and other data (excluding uploaded files).
#### Persistence
-`/var/lib/postgresql/data` is used to store the PostgreSQL database
On Kubernetes, with the default Helm chart and using the packaged PostgreSQL sub-chart, persistent data is stored in a PVC.
### Redis
authentik uses Redis as a message-queue and a cache. Data in Redis is not required to be persistent, however you should be aware that restarting Redis will cause the loss of all sessions.
#### Persistence
-`/data` is used to store the Redis data
On Kubernetes, with the default Helm chart and using the packaged Redis sub-chart, persistent data is stored in a PVC.
