Use the <br> tag to insert a line break. This tag ends the current line and moves remaining text to the next line.

<br> – singular tag (in XHTML, always close as <br />)

CODE EXAMPLE:

four calling birds<br />three French hens<br />two turtle doves<br />partridge nesting in a fruit tree.

RESULT:

four calling birds
three French hens
two turtle doves
partridge nesting in a fruit tree.