Java Transaction API or JTA is a Java programming interface that allows developers to manage distributed transactions in a Java environment. It provides a standard way to perform transactions across multiple Java resources, such as databases, message queues, and other services. JTA uses a two-phase commit protocol to ensure transaction atomicity, consistency, isolation, and durability (ACID properties), even in the event of failures or errors. Knowledge of JTA is essential for developers who work with enterprise Java applications that require transaction management.