Trim is the process of removing whitespace characters (spaces, tabs, newlines) from the beginning and end of a string. It is frequently used for user input validation and data cleansing.

JavaScript provides String.trim(), trimStart(), and trimEnd() methods. Python has str.strip(), and Java has String.trim(). JavaScript string methods books teach practical trim usage.

In character counting tools, trim affects the count, so offering users a choice between including or excluding whitespace is important.

Full-width spaces (U+3000) are removed by trim(), but non-breaking spaces (U+00A0) behave differently across languages. Data cleansing introduction books cover the full picture of text preprocessing including trim.