Use of que in "Tenemos que salir temprano"

I just cannot understand the seemingly random use of the word "que." Take this example, "Tenemos que salir temprano."  We have to leave early. There is no word "that, which, or who" in that sentence, there is no preposition, no connector. Why put the word "que" in it??

Kim 

"que" belongs to "tener" in this case: "tener que" means "to have to".

This is just one to remember.  You'll find that some verbs need a preposition or other connector when followed by an infinitive while others do not.  As Hundetier says, this particular combo means "to have to... "  Here are some common ones to remember.

Tener + que + infinitive = To have to do something.
​Tengo que comer = I have to eat.

Tener + ganas de + infinitive = To feel like doing something
​Tengo ganas de comer = I feel like eating

Ir + a + infinitive = Going to do something
​Voy a comer = I'm going to eat.

These are three of my favorites and come in quite handy.