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Trailhead has a nice overview of Page Layouts https://developer.salesforce.com/trailhead/force_com_introduction/customizing_user_interface/ui_page_layouts
Page Layout Notes
- If the user's profile does not have access to ALL fields in a section via Field-Level Security, then that section heading will not be shown. Nice to know.
Different Layout Types
Compact Layouts are for the Salesforce1 Mobile App. Mini Layouts are for Hover links and the Console.
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Trailhead has a nice overview https://developer.salesforce.com/trailhead/force_com_introduction/customizing_user_interface/ui_nav_buttons_links
The Stack Exchange questions at Make a button on a layout be visible only to a specific group of users have some great suggestions for buttons and links too.