When working with TYPO3 you often need the pages UIDs. These are not visible by default. With a line of code, the UIDs can be displayed directly in the page tree next to the page title.
Go to Backend users > [target user] > Edit > Options and enter the code below in the field TSconfig.
options.pageTree.showPageIdWithTitle = 1
That´s it! Reload your backend or log in with the target user to use a page tree with uids next to the page title.