This is a handy feature to save the workload of adjusting awkward uneven lines at the end of every single paragraph (usually left aligned) in a document, especially widows. I found that it works extremely well with multi-column document layout like newsletter as the paragraphs tend to be very narrow in width and this often cause ugly flows on every column right hand sides and also widows.
To turn it on or off, bring up Paragraph Palette (Command+Option+T) and click on the palette right facing arrow then you will find the feature Balance Ragged Lines. Use this feature with care as some times it might make your paragraph too short in width compared to the rest and probably the old soft returns with our manual adjustment will be better for this occasion.
