apt get - What do Inst and Conf refer to when using the command apt-get in Linux?

When I run the command apt-get install flashplugin-installer I am displayed the following lines of details

Inst flashplugin-installer [11.2.202.233ubuntu0.11.04.3] (11.2.202.235ubuntu0.11.04.1 Ubuntu:11.04/natty-updates [i386])
Conf flashplugin-installer (11.2.202.235ubuntu0.11.04.1 Ubuntu:11.04/natty-updates [i386])

What do Inst and Conf refer to? I am guessing Inst means installed however how does this relate to Conf? Does it mean confirm the installation of the said package?

Also why is the first package surrounded by square brackets e.g. [ whilst the second package is surrounded by brackets e.g. (?