In the book and publishing business, “justify” signifies how text is aligned within a page layout. It’s a typographical method that ensures the text lines up evenly on both the left and right margins.
Justifying means adjusting the spacing between words and letters to fill out the whole width of a column of text exactly, creating an even line along both sides. It can involve increasing or decreasing word spacing (the space between words) or altering letter spacing (tracking) when certain individual letters or characters are made bigger to make them fit better. It distributes type evenly across your page, making it look cleaner and more professional.
Justification is commonly used in most types of formal publishing – books, newspapers, magazines, etc. – and for some digital content. It’s one of several alignment options offered by word-processing software or desktop-publishing applications, sometimes set as default.
The benefits include improved readability: because justifying creates a smooth flow along each line, readers find it easier to follow your writing. Justified copy also looks polished and professional – which may enhance trust in you as an author or publisher, distributor, developer, or brand owner.
By adjusting word- and letter spacing just so you can use space far more efficiently, too; i.e., get more text onto an average-size page than if you were working with a ragged-right copy because justified columns do away with those uneven gaps that typically appear at paragraph ends when using left-aligned, ragged-right copy (what I call ‘the tyranny of justification’), they promote visual consistency over long documents.
Justifying might give a document, piece, statement, video, etc. Extra gravitas by association with traditional publishing models, formats, and principle, if not done, excessive/unbalanced spacing adjustments can introduce gratuitous white-river effect or gaps-between-words denser-than-others phenomenon, which is counter-productive from legibility or design points of view.