The second class of Sparta
(the first being the Spartan citizens, and the third being the Heilotes
). The meaning of the name is : 'Those who Live Around'.
The perioikoi actually lived mainly along the Laconian shore. Their origin isn't clear. Some researchers believe that they were the descendants of the upper-classes of the pre-doric peoples who lived in the region before the Doric invasion, others say that they were Dorians (like the Spartans themselves), but were of other cities of Laconia that were subjugated by Sparta.
The perioikoi had internal independence where they lived, and partial ownership over some of the lands of their places of residence. They participated in war, and received similar training to that of the Spartan citizens, but couldn't make it to high commanding positions (and since the military was the backbone of Spartan society, it naturally influenced their status within it).
They had no part in the institutes of the polis (i.e. couldn't vote or be elected) and had no say in determining the policies of the polis. They dealed mainly in commerce and workmanship.
During the years, many Spartans who lost their wealth and couldn't make a living without working, lost their citizenship and joined the perioikoi. This caused much dissention, and many of the new perioikoi aided the Messenians in their rebellions.