Though all teeth are covered in enamel, the natural protective coating, the bacteria that gets stuck in deep pits & grooves can eat away at it & the tooth virtually unimpeded. This leads to cavities that might require costly and potentially painful restorative work.
Anyone can get a sealant, but they are most commonly recommended for children as their adult teeth start to replace their primary teeth. Having that extra protection from the beginning can keep children cavity-free through their school years. This means families can save money by preventing costly restorative work, & the children can focus on school without getting distracted by toothaches & dental appointments.