Custom tab types
Key Takeaway
Pick the custom tab type that matches the content you want to show and the place users need to see it: Salesforce Classic, Lightning Experience, or the Salesforce mobile app.
A custom tab gives users a way to reach custom object records or other web content from inside Salesforce. There are five custom tab types, and each one suits a different kind of content.
Where custom tabs appear
In Salesforce Classic, a custom tab added to an app appears as a tab. In Lightning Experience, it appears as an item in the app's navigation bar and in the App Launcher.