Exist because double bonds don't rotate freely. Have different properties of course, unlike enantiomer.
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Cis–trans isomerism, also known as geometric isomerism, is a type of stereoisomerism where the spatial arrangement of groups or atoms in a molecule differs due to the restricted rotation around a double bond or within a ring structure. Here’s a breakdown of the concept: 1. **Cis Isomer**: In a cis isomer, similar or identical groups are positioned on the same side of a double bond or a ring structure.