Words, Phrases and Clauses
These are the three central grammatical structures which make up all sentences.

• A phrase consists of one or more words and is a part of a sentence.

• Whilst technically a phrase can be a single word, it's easier to think of multi-word phrases as being an 'extended word'. We might have about half a million individual words in our language but we still don't have enough to cover every eventuality. A phrase is our way out: it's a word with extra identifying or 'modifying' words added to it, e.g. 'the hissing and spitting black cat'.

• A phrase (one or more words) is the smallest group of words that can occupy a grammatical 'slot' within a sentence.

• It will always have a coherent and unified meaning (this is because all phrases are single words or built around a single word. This is the so-called head of the phrase, its head word.

• The remaining words within a phrase are always grammatically linked to the head word and function to modify or add extra information to the head word.

• A phrase, if it is made up from more than one word, can always be substituted by a single word (which will never be quite as full or clear in meaning, but can be a substitute).

• A phrase can never be sufficient to create a sentence or clause on its own (except in speech when almost anything goes within certain informal contexts).

Head Word
Here is a phrase: ...the unusually strong creature...

• Can you tell that the meaning this phrase creates is coherent and unified - and yet that it is insufficient in itself to make a complete grammatical sentence?

• Can you also see why its head word is creature and that the three remaining words: the, unusually and strong are acting to modify the head word and so refine its meaning?

• Phrases are named according to the grammatical function they perform within their sentence. Thus, the above phrase, being built around a single noun as its head word, is called a noun phrase.

Grammatical Units
Being able to identify the number of separate grammatical units or structures that exist within a sentence is a central skill that you will pick up as you learn more about grammar. It's something that comes with knowledge and practice but you might be surprised how easy it can be. Can you work out how many separate grammatical units there are in the following - rather wordy! - sentence?

Down by the river as the clock struck one, in a frenzy and with a loud scream, he grabbed the intruder by the scruff of the neck.

Did you count seven? If so, well done. Six of them are phrases and there is a seventh different grammatical structure called a clause. The clause is shown in grey below (technically it's also composed of phrases, in this case three: he grabbed the intruder - this is covered later under 'clauses').

Down by the river as the clock struck one, in a frenzy and with a loud scream, he grabbed the intruder by the scruff of the neck.

• The words in many of these phrases indicate such things as position in time and space, or manner. These are called prepositions: 'down', 'as', 'in', 'with', 'by' and 'of'. These are the head words of prepositional phrases. You'll read more about these later.

Clauses
Clauses consist of two or more phrases and, like phrases, form coherent units of meaning.

• A clause tells about action or state (i.e. what a thing is doing or being, e.g. 'He grabbed a brick'; 'She felt ill'.

• Typically, a clause is composed of a noun phrase (acting as subject) and a verb phrase.

• If something is acted upon by the subject, it fills the grammatical object position.

The 'Predicate'

• The predicate is a term sometimes used to describe all of the clause apart from the subject, i.e., it tells what the subject is doing (and to what).

• In the above example, the full grammatical subject is, 'Down by the river as the clock struck one, in a frenzy and with a loud scream, he...' and the predicate is, therefore, '...grabbed the intruder by the scruff of the neck.'

• The structure of any clause, therefore, is subject + predicate.

Phew....! That's an awful lot of grammar to digest for one web page! Fear not - it won't happen again. Time for a breather, then maybe a quick re-read through to make sure it's all sunk in?