The creative side of photography lives here. Side light brings out texture, direct side light gives deeper, longer shadows, indirect side light softens and flatters in portraits.
Side light can be the most dramatic light, but we need to be careful how we use the tool as it can emphasize flaws.

Father Cam, 1968. Shot on Ilford HP4 film with one flash in front of the subject.

Side light at Yosemite Valley emphasizes the rugged landscape.

Diffuse side light flatters the subject with soft shadows.