Answer in brief
A phrasal verb is a verb plus one or two particles, such as call off or put up with, and the particle usually changes the meaning: call means to telephone, call off means to cancel. Some can be split by their object and must be split by a pronoun (call it off); others never split (look after her). Learn each meaning in a full sentence and review it at growing intervals.
A verb, a particle and a meaning of their own
Phrasal verbs are why a learner can know every word in a sentence and still miss its meaning. The British Council's LearnEnglish grammar page describes them as a verb with one particle or sometimes two, and notes that the particle often changes the meaning: call is to telephone, call off is to cancel. Wikipedia's article on the phrasal verb calls the pair a single unit of meaning, to be taken as a whole. Nothing in give or up tells you that give up means to stop trying, which is how Oxford Learner's Dictionaries defines it.
They span every level. Oxford Learner's Dictionaries tags many senses with a CEFR level, the scale its Oxford 3000 core word list is aligned to. Find out, to get information by asking or reading, is tagged A1, and so are get up and wake up, to stop sleeping. Look forward to, come up with and end up sit at B1, get over and figure out at B2, get away with at C1.
Adverb particles, prepositions and verbs without an object
The small word after the verb is a particle: up, down, in, out, on, off and into, which older grammars, Wikipedia notes, analysed as adverbs. The same words also work as prepositions, and that decides word order. Wikipedia's shift test tells them apart: a preposition never moves behind its noun, so you bank on Susan but never bank Susan on, while a particle can, so take Susan on is fine. If the word can jump over the object, the verb can split.
Then check whether there is an object at all. Oxford Learner's Dictionaries writes this into the headword: give up stands alone, while give something up means to stop doing or having something, as in giving up sugar. Take off without an object is what a plane does when it leaves the ground; take something off is what you do with a coat. Grow up, end up, turn up in the sense of arrive, and break down for a car that stops working usually stand alone.
Separable and inseparable phrasal verbs: where it and them go
The British Council sorts phrasal verbs by word order into two main types. With separable ones the object may sit after the particle or between the parts: they called off the meeting, or they called the meeting off. With a personal pronoun there is no choice: they've called it off. So you pick it up, turn it down, bring it up and fill it in, which for a form means to complete it, but never pick up it. Long objects tend to stay at the end, Wikipedia notes: turn down the offer that came from head office.
Inseparable verbs keep the parts together even with a pronoun. The British Council lists look after, as in who looks after her while you work, and come across, to find by chance. Its other examples are get over, to recover from something, and look into, to investigate, as in we are looking into it. The headword shows which kind you have: Oxford writes turn somebody or something down with the object inside, and look into something with the object after.
Three-word verbs: put up with, look forward to, run out of
Wikipedia calls verbs with two particles particle-prepositional verbs; the British Council says they never split, so a pronoun goes after both particles. In Oxford's entries put up with is to accept something annoying without complaining, synonym tolerate, and run out of is to finish a supply, as in we ran out of milk. Cut down on is to reduce, come up with is to find or produce an answer, and get away with is to do something wrong and not be punished. The British Council adds get rid of, to become free of something unwanted.
One trap catches many learners. In look forward to, the to is a preposition, so Oxford gives the pattern look forward to doing something: write I look forward to hearing from you, never to hear. Get away with follows the same pattern, as in he got away with skipping the meeting. Put up with takes a noun or a pronoun after it, as in how do you put up with them.
One spelling, many meanings: take off, pick up and phrasal verbs with get
Oxford Learner's Dictionaries lists take off for a plane leaving the ground at A2, for leaving a place in a hurry as informal, and for an idea or product that suddenly becomes successful at C1. With an object it means to remove clothing, to take time off work or to cut a total, as in ten dollars off the bill. That is six meanings behind one spelling, from beginner level to advanced. Pick up is just as busy: to lift something at A2, to collect someone in your car at B1, to learn a skill by chance at B2, to improve, as trade does in spring, and to answer the phone.
Phrasal verbs with get show the same spread. In Oxford's entries get up is to get out of bed, get back is to return home, and get over is to recover after an illness, a shock or the end of a relationship. Get on with someone is to have a friendly relationship, get by is to manage with the money or knowledge you have, and get through is to complete a task or to reach someone by phone. In British English, Oxford adds, get through also means to pass an exam.
Single verbs in formal writing, and British versus American labels
The British Council notes that these verbs are very common, especially in more informal contexts, and Oxford tags some senses as informal: show up for arriving, hold on for asking someone to wait. Many have a one-word synonym in the same entries: put off is postpone, get over is overcome, bring up a child is raise. In a report, will investigate the complaint reads tighter than will look into it, while in conversation I can't put up with this noise is simply how people talk. Yet not all are casual: Oxford pairs carry out with an inquiry or a survey and gives no informal label.
Oxford's labels also mark British and American use. Fill something in is especially British, while fill something out is British and North American. Get on with someone is British, and get along with someone is used in both. Catch somebody up is British beside catch up with, and give something in is British beside hand in. Especially marks a tendency, not a border, so pick one variety per text and keep to it.
How to learn phrasal verbs so they stay in memory
Grouping by particle helps you guess and remember. Up often means finishing completely: to use something up is, in Oxford's words, to use all of it so that none is left. Off often means leaving, as when you set off on a journey; out often means discovering or solving, as in find out and sort out; down often means reducing or refusing, as in turn down and cut down. Treat these as hints, not laws: look up can mean that things are improving, and nothing in down explains why a machine breaks down.
Learn every verb in a full sentence that shows its object, the place of the pronoun and its usual partners: turn it down, look after her, carry out a survey. Wikipedia describes spaced repetition as an evidence-based technique, usually done with flashcards, in which new and difficult cards return more often. It traces the idea to Hermann Ebbinghaus in the 1880s and his forgetting curve, a graph of how learned information is lost over time. A good card hides the particle, not the verb, so it asks for the out in we ran out of milk. Then say the verbs aloud by telling your day: I got up late, set off at nine, ran into a friend and ended up staying for lunch.
Practising phrasal verbs alone, and what a structured course adds
A realistic week alone looks like this. Take ten verbs from this page, two from each particle group, and write two sentences for each, one with a noun object and one with it or them. Check each headword in a learner's dictionary for object position, level and any British or American label. Review the cards the next day, a few days later and at the end of the week, and record yourself telling a short story with all ten.
Alone, nobody corrects you and the list stays flat, with A1 and C1 meanings mixed. The English in 213 Days course of VITON13 SCHOOL builds the order in: each day has a bank of 52 words and phrases in four sets of 13, and one set holds verbs, phrasal verbs and idioms, with everyday verbs up to A2, phrasal verbs at B1 and B2, and idioms at C1 and C2. Every word and phrase joins a card deck, and the FSRS algorithm brings each card back on the day the learner starts to forget it. Explanations are in Russian, French, Spanish, German or Portuguese. The first three days are free, as is the adaptive placement test, and English Logic builds phrases as a chain of questions.
Practical checklist
- Pick ten verbs: two each with up, off, out and down, plus two three-word verbs.
- Write two sentences for each verb, one with a noun object and one with it or them in the right place.
- Check each headword in a learner's dictionary for object position, CEFR level and a British or American label.
- Make cards that hide the particle, and review them the next day, a few days later and at the end of the week.
- Tell a short story aloud about your day using all ten verbs, record it and listen for the word order.
Questions and answers
Is it wrong to say pick up it instead of pick it up?
Yes. Pick up is separable, and with a personal pronoun such as it, them or her the pronoun must sit between the verb and the particle. A noun can go in either place, so pick up the box and pick the box up are both correct, but only pick it up works with the pronoun.
How can I tell whether a phrasal verb is separable?
Look at the headword in a learner's dictionary. When the entry is written as turn something down, the object can go inside; when it is written as look into something, the object always follows. The shift test helps too: if the small word can move behind its object, it is a particle, and the verb can be split.
Are phrasal verbs too informal for an essay or a cover letter?
Not all of them. Carry out, set up and point out carry no informal label in Oxford Learner's Dictionaries. Others are marked informal in dictionaries, such as show up or hold on, and some read better as one verb in formal writing: postpone instead of put off, investigate instead of look into, tolerate instead of put up with.
Why is it look forward to seeing you and not to see you?
Because the to in look forward to is a preposition, not part of an infinitive. A preposition is followed by a noun or an -ing form, so the dictionary pattern is look forward to something or look forward to doing something. The same goes for get away with doing something.
What is the best way to learn phrasal verbs for speaking?
Learn a small set at a time, each in a sentence of your own with its object, and group them by particle. Review the sentences at growing intervals with cards that hide the particle. Then use them out loud the same day, for example by describing your morning, because recognising a verb on a page and producing it in speech are separate skills.