When browsing with Safari it will open new windows each time certain types of links are clicked, this can result in many windows being created. This tweak opens those new windows as Tabs instead.
Start a new Terminal session (in Finder click Applications > Utilities > Terminal).
To enable this setting, type (or copy and paste) the following command:
defaults write com.apple.Safari TargetedClicksCreateTabs -boolean true
To reset this setting to the default value, type (or copy and paste) the following command:
defaults delete com.apple.Safari TargetedClicksCreateTabs
To activate this tweak please close all instances of Safari, or wait until the next reboot.
Close the Terminal session by typing
exit at the prompt.
Disclaimer: Making any changes to your system can cause serious problems that may require you to reinstall your operating system. We cannot guarantee that problems resulting from these modifications can be resolved. Please follow the instructions carefully and use the information provided at your own risk.