01. To refer to something which is generally true or universal.
La Tierra gira alrededor del Sol (Earth rotates arounth the Sun).
02. To refer to habitual actions.
Duermo unas ocho horas (I sleep about eight hours).
03. To express habilities
Ramón toca muy bien el piano (Ramon plays the piano very well).
04. To refer to an action of state of affair which is valid in the present.
Mis padres viven allí (My parents live there).
05. To refer to timeless situation.
Me gusta viajar (I like to travel).
06. To refer to actions taking place al the moment of speaking.
Los niños juegan en el jardín (Children are playing in the garden).
The present progressive is also possible in these sentences.
07. To refer to the future, especially, pre-arranged events and, generally, with verbs of movement.
Mañana llega Antonio (Antonio is arriving tomorrow).
08. To refer to an action that began in the past and is still in progress.
Hace 10 años que vivo aquí (I have been living here for 10 years).
09. To refer to the past (historic present).
La Guerra Civil Española empieza en 1936 (Spanish Civil War started in 1936).
10. As an imperative, especially in directions and instructions.
En la esquina doblas a la derecha (You turn right at the corner).