Line Break in a Cell

To insert a line break in a cell, simply press Alt + Enter:

excel line break alt enter


Automatic Line Break

Another solution is to automatically wrap text by clicking on Wrap Text:

excel automatic wrap line break

The display will then adapt according to the width of the cell:

excel automatic wrap width line break

Note that this option is also accessible by right-clicking on the cell and then selecting Format Cells:

excel automatic wrap format cells line break