Text justification, also called text alignment, refers to how text lines up between the vertical margins. If text is left-justified, as it should be in APA style, the text is aligned or even on the left margin and "ragged," or having uneven line lengths, on the right margin. Left-justified text is the default in many word-processing programs. Right-justified text is even on the right margin and ragged on the left-margin. Centered text is ragged on both margins. Justified text is even on both margins and does not have a ragged edge, but justifying text sometimes creates awkward spaces between words.
Justifying Other Page Elements
While body text should be left-justified, other parts of your paper should be centered or right-justified. Your running header, for example, should be left-justified, while your page number should be right-justified. The headings for your title page, author note, abstract, method, results, discussion, conclusion and references should be centered on the page. However, tables, figures, legends and captions should be left-justified.