Rev(erse) a list. erse ends up appending all elements once it gets to the end, while erse_tail will reverse as it goes.

rev.erl

-module(rev).
-export([start/0,erse/1,erse_tail/1]).

%% recursion with appending
erse([First|Rest]) -> erse(Rest)++[First];
erse([]) -> [].

%% tail recursion
erse_tail(L) -> erse_tail(L,[]).
erse_tail([],New) -> New;
erse_tail([H|T],New) -> erse_tail(T,[H|New]).

%% test
start() ->
    N = 10000,
    List = lists:seq(1,N),
    {Time,_} = timer:tc(rev,erse,[List]),
    {Time2,_} = timer:tc(rev,erse_tail,[List]),
    %% using the built-in function
    {Time3,_} = timer:tc(lists,reverse,[List]),
    io:format("Appending ~p ms~n",[Time/1000]),
    io:format("Tail recursion ~p ms~n",[Time2/1000]),
    io:format("BIF ~p ms~n",[Time3/1000]).