Feedback. Depend on or depend of?
You probably got numbers such as more than 150,000,000 for depend on and less than 400,000 for depend of. This most likely gives you an idea of which one of the combinations is correct – or at least more frequently used!
In general, taking a look at the type and/or countries of origin of the Internet pages listed as search results also gives you useful hints on the correctness. For example in the listing for “depend of” you can find several websites from countries the official language of which is not English – a good hint that the use of this verb-preposition combination may be more common among the non-native speakers of English. Grammatically incorrect English can also be often found in chatrooms, blogs and discussion groups. Furthermore, many of the listed depend + of combinations were actually sentences of the type "..depend, of course, on....", but Google is not able to separate these from the actual occurrences of "depend of".