Text Sort

Yes, enable the duplicate removal option to automatically remove identical lines.

Yes, select numerical sort mode so 10 sorts after 2, not before.

Yes — instead of comparing raw character codes, it uses the browser's locale-aware collation. That is why German ä sorts right after a while Swedish ä sorts after z, each following its own dictionary convention. Korean orders by initial, medial and final jamo, Japanese follows kana order, and mixed capitalization keeps A and a together instead of scattering them.

Sorting only produces a new result; the text you typed stays in the input box, so copying it again restores the original order. Once you paste the sorted output back over the input, though, there is nothing to recover. For a list whose order carries meaning, prefix each line with a number such as 001, 002 — sorting by that number later brings the arrangement back exactly.