Use the Tabs pane of Safari preferences to set options for opening webpages in tabs.
⌘-click opens a link in a new tab (Mac)
Ctrl-click opens a link in a new tab (Windows)
To change the shortcut for opening a link in a new tab, select or deselect this checkbox.
When a new tab or window opens, make it active
To have new tabs or windows open in front of the one you’re currently viewing, select this checkbox.
Confirm before closing multiple tabs or windows
When you close a Safari window that contains multiple webpages open in tabs, all those webpages close. Select this checkbox if you want to see a warning message when you close a Safari window that contains multiple tabs.
Some keyboard shortcuts change depending on which options you select in Tabs preferences. The list at the bottom of the Tabs pane shows you the keyboard shortcuts.