Choose which kinds of whitespace to clean up and see the tidy result.
Each cleanup is a separate switch. Trimming removes spaces and tabs at the start and end of every line. Collapsing replaces runs of several spaces with one. You can convert tabs to spaces, delete blank lines, or remove every space while keeping line breaks.
A separate option replaces non-breaking spaces, thin spaces and other lookalikes with ordinary spaces and deletes zero width characters. These invisible characters are a common reason that two strings that look the same are not treated as equal.
No. Line breaks are kept. Use the Remove Line Breaks tool to join lines.
A space that looks normal but prevents a line wrap. It often arrives from web pages and word processors and is a different character from an ordinary space.
Yes, collapsing turns leading runs of spaces into one. Turn that option off, and trim off, if you need to preserve indentation.