Where is the stress in long words?

advertisment, advertise

In words such as advertisment, advertise we often don't know what part of the word is 'stressed' (= what part of the word is pronounced with extra force).

Let's look at the word divided into its parts:

We write 

ad-ver-tise-ment, ad-ver-tise

We hear

ad-VER-tise-ment, AD-ver-tise

Similarly we hear

STRA-te-gy, stra-TE-gic

The 'stress' has shifted from the second part to the first!

There are words where the stress shifts even more:

pho-TO-gra-phy, PHO-to-graph, pho-to-GRA-phic