The size can be variable – medium (genera Libellula and Orthetrum) or small (Sympetrum). The eyes are broadly confluent, their abdomen is wide and flattened in the Libellula genus and cylindrical in Sympetrum and anal appendages are small.

Species belonging to the Libellula genus feature a typical black triangular patch at the hindwing base. The rest of the wing is usually hyaline, even if a few species have some spots at the forewing base or in other parts of the wings. Sometimes females wings are yellow or shaded at the tip. They have more than 13 antenodal veins on the forewings.

Sexual dimorphism is striking (males often feature pruinosity). Colors in males are very variable, from pale blue (genera Libellula and Orthetrum) to red (genus Sympetrum).

These species are mainly observed in still waters and are very territorial, with strategical perches in sunny places. Mating is quick and occurs in flight. Oviposition is usually exophytic and females in the Libellula genus oviposit alone: the water is hit by the female with the abdomen tip, often with males guarding. In the Sympetrum genus oviposition occurs often “in tandem”. The eggs are fixed to the underwater substrate glueing together in a gelatine secerned during ejection.