If/Else

local age = 10
if age < 18 then
    print("under 18")
end

age = 20
if age > 18 then
    print("over 18")
elseif age == 18 then
    print("is 18")
else
    print("under 18")
end

==, <, >, <=, >=, ~= (inequality)

local isAlive = false
local age = 19
if isAlive and age > 18 then
    print("good")
elseif not isAlive or age < 18 then
    print("either dead or under 18")
end