There is a grammatical part of the sentence called (i think...) DATIVE, מושא in hebrew.
It can be direct or indirect. and in both cases can be articled or not.
The word את is used in Direct Dative AND articled. example:
Indirect Dative is when you have a prepositional used, like on, at, from. etc..:
I jumped on a floor
אני קפצתי על רצפה
...now with article:
I jumped on the floor
אני קפצתי על הרצפה
...or without article:
I ate an apple
אני אכלתי תפוח
NOW, when you have article and you dont use a proposition, there you put the lovely את
I ate the apple
אני אכלתי את התפוח
it is said that David Ben Gurion, the first prime minister of Israel used to speak with no את. I think that technically it is correct and can sound even poetic/archaic sometimes.
please beware: In news papers'head-lines they sometimes drop the את for shortage of space.