> For the complete documentation index, see [llms.txt](https://reyvaleza.gitbook.io/vibe.d-tutorial/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://reyvaleza.gitbook.io/vibe.d-tutorial/authentication-and-authorization.md).
# Authentication and authorization
We need to restrict access to sensitive parts of our site so only authorized users (admins) can make changes to sensitive data. We need a login system to authenticate and to authorize users.
Authentication means verifying that the user is who he/she says he/she is. Authorization means determining which parts of the application the user is allowed access.
In a commercial company, only a limited number of people are supposed to access sensitive data such as employee records.
To achieve this, we need a login system to authenticate and authorize users.
Click on the Login link on the menu to show the login form and fill out with an existing data.
Of course, when you click the **Login** button, you get an error:
Let us fix that. Let us do the authentication part of the login system.
