Materials that do not allow electric charge to escape outward act as:

1. Materials are grouped by how freely charge moves through them. 2. Some materials hold charge in place rather than letting it flow away. 3. These materials act as insulators that do not allow electric charge to escape outward. 4. Conductors instead let charge move freely. _Source: OpenStax College Physics for AP Courses 2e (CC BY 4.0), Ch 18 'Electric Charge and Electric Field', sections 18.1-18.8_