1. As you have seen above, it is formed from the present tense of ESTAR and the GERUND of the main verb:
Estoy comiendo paella (I am eating paella).
Estamos trabajando en proyecto nuevo (we are working on a new project).
¿Quién está llamando a la puerta? (Who is knocking the door?).
2. Just at a glance, to form the gerund we will take the ending of the infinitive and we will add –ando (for those ending in -ar) or –iendo (for other two groups) and is the same as the –ing form of the verb in English:
- Escuchar (listen) – .. = escuchando (listening).
- Comprender (understand) – ..= comprendiendo (understanding).
- Recibir (to receive) – .. = recibiendo (receiving).
Although there is a small group of verbs that made their gerund in an irregular way: leer ( to read): leyendo; decir (to say): diciendo; construir (to build): construyendo; poder (to can): pudiendo; dormir (to sleep): durmiendo.… Learn more about el gerundio (gerund).