What is a string I need help, I see this everywhere but can't find the answer. ???

A string is a word or sentence that can be used as an instance!

local string = "Word"
local otherstring = "some other words"

A string can be used in many ways which you can see in this link: http://wiki.roblox.com/index.php?title=Global_namespace/String_manipulation

A string can also be a value

for example: there is a string in worspace called "Rarity" and the value is common

if workspace.Rarity.Value == "Common" then
	print("Object is a common object")
else
	print("Object is not common")
end

as you see "Common" is the string, strings work in many ways and can be used many times for many reasons..

Even small things like text inside a textlabel or even a "Byte" is a string

Anyways, this is my definition, I prefer you hear more from other people