WordPress Toolbar: Justify text
The justifying text buttons align the text to the left, center or right while the full justification creates alignment across the full width of the content area so that text is straight instead of ragged on the left and right side. Full justification can be tricky on a website where it is difficult to add hyphenation. The usual result of a fully justified column is that some lines will have odd spacing between words making the line look awkward and rendering it difficult to read. For that reason it’s best to avoid full justification on your website in most cases.