You are a developer asked to create a bot that will provide an overview of...

 member_joined_channel (often referred to as member_joined in event grouping contexts): This event is triggered when a standard user joins a public or private channel. Subscribing to this allows your bot to see whenever someone joins #it-help and instantly send them the welcome overview and resources guide.

 channel_joined: This event is specifically sent to your application when the bot user itself is added to a channel. Subscribing to this ensures your bot knows it has been successfully added to #it-help so it can begin its duties or send an initial greeting.

 app_mention: This event explicitly handles instances where users mention the bot (e.g., @ITHelpBot how do I connect to the VPN?). Subscribing to this lets the bot listen for and respond to specific user queries without needing access to read every single regular message in the channel.