Taran Killam and Jay Pharoah <| sep |> It looks kind of like an Olympic torch patch ? <| sep |> What ' s annoying is that they have meaning . The people using them don ' t seem to appreciate this . <| sep |> That ' s alright , and it probably wont cause too many issuesIt still can cause problems if you do it too much , in that your code will be obnoxious as hell to maintain , and the more includes you do , the more likely you ' re to include something redundant further down the lineThe real issue occurs in examples like this where you have ' webs ' of inclusion . Where state . h was included , and another . h file which itself incldued state . hThings like this not only quickly lead to mazelike dependency and honestly tons of redundant inclusions , but also , if not for header guards , multiple definition errors . EDIT Compilers handle multiple inclusion pretty well . so it ' s more on principle of not making a messy inclusion web than any REAL need not to .