What does caret (^) in Ubuntu’s apt-get command mean?

[ Thanks to An
Anonymous Reader
for this link. ]

“If you have come across a tutorial or just someone on
a forum who tells you to install something in Debian/Ubuntu that
involves using apt-get, it is ok for you but when they tell you
that you need to use a caret symbol (^) at the end, that’s where
you become curious. What is even more weird is that when you search
for the name of the package that the given command seems to install
cannot be found using apt-cache search. e.g. You will see this used
most often when someone tells you how to install LAMP server setup
(Linux-Apache-MySQL-PHP) by using the command “sudo apt-get install