All vs. All of

Excerpt from English Grammar In Use:


You don't need of after all or half. So you can say:

• All my friends live in Los Angeles. or All of my friends...
• Half this money is mine. or Half of this money...

Compare these sentences:

• All flowers are beautiful. (= all flowers in general)
• All (of) the flowers in this garden are beautiful. (= a particular group of flowers)

Before it/us/you/them you need of after all and half (all of, half of):

• all of us (not all us)
• half of them (not half them)