Justified alignment

Justified text stretches each line to reach both edges, except the last line of a paragraph. In the example, both edges line up and the spacing between words changes from line to line.
It is common in printed books and newspapers, where careful hyphenation keeps the gaps even.
On screens, especially in narrow columns, justified text often creates uneven gaps and "rivers" of white space. These make reading harder, especially for people with dyslexia, so prefer flush left for digital body text.