Compact layouts for the highlights panel
Key Takeaway
A compact layout is an ordered list of an object's key fields that appears in the highlights panel at the top of a record. You assign it to the whole object as the primary compact layout, or to specific record types, but not to profiles or individual users.
A compact layout is a short, ordered list of an object's key fields. Salesforce shows these fields at the top of a record, in the highlights panel, so users see the most important information at a glance. Compact layouts are used in Lightning Experience, the Salesforce mobile app, and the Outlook and Gmail integrations.
Each object has its own compact layouts
Each object has its own compact layouts, just as each object has its own page layouts. Compact layouts are available in Salesforce Classic and Lightning Experience in all editions except Database.com.
Every object has a system default compact layout, which is read-only. By default, the object takes its record highlight fields, preview cards, and action-related feed items from this system default, so you don't have to create a compact layout. Salesforce recommends custom compact layouts to put important fields into record headers.
Compact layouts and page layouts are independent, so removing a field from a page layout does not remove it from the compact layout. A change to a compact layout shows up in both Lightning Experience and the Salesforce mobile app.