β-Chlorobutyric acid is a common name for a compound where:

• The parent chain is butanoic acid (a four-carbon chain with a carboxylic acid functional group).
• A chlorine atom (\( -Cl \)) is attached to the second carbon (β-carbon) in the chain.

In the IUPAC system, the chain is numbered starting from the carbon of the carboxylic acid group, and substituents are named based on their positions.