"Qualifying children" refers to the criteria used to determine if a child can be claimed as a dependent on a tax return. To qualify, the child must meet specific age, relationship, residency, and support tests. Generally, the child must be under 19 years old, or under 24 if a full-time student, and must live with the taxpayer for more than half the year. These rules are important for taxpayers because claiming a qualifying child can lead to various tax benefits, such as the Child Tax Credit and Earned Income Tax Credit. Understanding these criteria helps families maximize their tax savings.