Getting a String from a list of strings

Supporting the maxim "there is always another way to do it":

list = {"M","a","t","h","e","m","a","t","i","c","a"};

StringJoin accepts lists directly, and in fact is faster this way:

StringJoin @ list
"Mathematica"

Also, StringJoin has the short form <> therefore you could also use:

"" <> list
"Mathematica"

Speed check:

large = Characters@ExampleData[{"Text", "LoremIpsum"}];

Do[StringJoin @@ large, {5000}] // Timing

Do[StringJoin @ large, {5000}]  // Timing

Do["" <> large, {5000}]         // Timing

Version 7.0.1 timings:

{1.622, Null}

{0.702, Null}

{0.718, Null}

Version 10.1.0 timings:

{0.6864, Null}

{0.4524, Null}

{0.4524, Null}

Just for something different Fold works too:

Fold[#1 <> #2 &, "", {"M", "a", "t", "h", "e", "m", "a", "t", "i", 
  "c", "a"}]

"Mathematica"

Use StringJoin:

StringJoin @@ {"M", "a", "t", "h", "e", "m", "a", "t", "i", "c", "a"}

"Mathematica"