What are the child windows and parent windows of session?

Does the

child window refer to clicking on the link without jumping out of the window and constantly entering the link?
if you click a link and jump to a new page, this is a new parent window, that is, the beginning of a session?

Mar.09,2021
MySQL Query : SELECT * FROM `codeshelper`.`v9_news` WHERE status=99 AND catid='6' ORDER BY rand() LIMIT 5
MySQL Error : Disk full (/tmp/#sql-temptable-64f5-1bc8db7-3091b.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
MySQL Errno : 1021
Message : Disk full (/tmp/#sql-temptable-64f5-1bc8db7-3091b.MAI); waiting for someone to free some space... (errno: 28 "No space left on device")
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