What is gcinfo()?

so i discovered that this thing after reading memory leaks forums:

while wait(.5) do
print(gcinfo())
end

i played on my game a bit and i discovered that everytime i used a tool the gcinfo will print 10 numbers above the last print. i was trying to optimize my code to make the numbers lower until i found out that i really dont know whatis this printing, and there are no documentations about

in short, what is gcinfo?