A justified text is a block of text with each side aligned.

Depending on the length of the line, it often occurs that some of them don’t look even: too loose because of not enough words on the same line, or too compact with a long and unbroken word at the end.
Typographers would either adjust the tracking to fit more words or symbols in a line, and/or use hyphenation to ‘break’ words that are too long.

Some other type setting options (common for scripts written horizontally and from left to right) are centered, flush left / ragged right.