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Phrasal verbs
The term phrasal verb is commonly applied to two or three distinct but related constructions in English: a verb and a particle and/or a preposition co-occur forming a single semantic unit. This semantic unit cannot be understood based upon the meanings of the individual parts in isolation, but rather it must be taken as a whole. 
One can discern at least three main types of phrasal verb constructions depending upon whether the verb combines with a preposition, a particle, or both. 

• Verb + preposition (prepositional phrasal verbs)

a. Who is looking after the kids? - after is a preposition that introduces the prepositional phrase after the kids.
b. They pick on Billy. - on is a preposition that introduces the prepositional phrase on Billy.
c. I ran into an old friend. - into is a preposition that introduces the prepositional phrase into an old friend.
d. She takes after her mother. - after is a preposition that introduces the prepositional phrase after her mother.
e. Sam passes for a linguist. - for is a preposition that introduces the prepositional phrase for a linguist.
f. You should stand by your friend. - by is a preposition that introduces the prepositional phrase by your friend.

• Verb + particle (particle phrasal verbs)

a. They brought that up twice. - up is a particle, not a preposition.
b. You should think it over. - over is a particle, not a preposition.
c. Why does he always dress down? - down is a particle, not a preposition.
d. You should not give in so quickly. in is a particle, not a preposition.
e. Where do they want to hang out? - out is a particle, not a preposition.
f. She handed it in. - in is a particle, not a preposition.

• Verb + particle + preposition (particle-prepositional phrasal verbs)

a. Who can put up with that? - up is a particle and with is a preposition.
b. She is looking forward to a rest. - forward is a particle and to is a preposition.
c. The other tanks were bearing down on my panther. - down is a particle and on is a preposition.
d. They were really teeing off on me. - off is a particle and on is a preposition.
e. We loaded up on Mountain Dew and chips. - up is a particle and on is a preposition
f. Susan has been sitting in for me. - in is a particle and for is a preposition.