This article describes an outdated approach to Slack apps. Modern Slack apps are installed with the V2 OAuth 2.0 flow. OAuth 2.0 is a protocol that lets your app request authorization to private details in a user's Slack account without getting their password. It's also the vehicle by which Slack apps are installed on a team. Your app asks for specific permission scopes and is rewarded with access
![Legacy: OAuth 2.0 for legacy Slack apps](https://cdn-ak-scissors.b.st-hatena.com/image/square/c9bf2b7d09dea24cef89b3381720b312dd379eb4/height=288;version=1;width=512/https%3A%2F%2Fa.slack-edge.com%2F80588%2Fimg%2Fservices%2Fapi_200.png)