Running, jumping, skiing, thinking, talking, ...
Corriendo, brincando, esquiando, pensando, hablando ...
The present participle is formed by taking off the last two letters of a Spanish verb (-ar, -er, or -ir) and replacing it with -ando (-ar verbs) or -iendo (-er and -ir verbs).
Estar > estando
Comer > comiendo
Ser > siendo
Contar > contando
The slightly irregular ir > yendo