Mathematica is fanatic about exactly correct capitalization and use [] versus () versus {} and use of = versus := versus == and there is even an === and those are all different. Make any tiny error in any one of those and you will get incorrect results or error messages you don't know how to interpret or even nothing at all.
In[1]:= Plot[Sin[x], {x, -2 Pi, 2 Pi}]
Out[1]= <<<plot snipped>>>
