The main concentration is on sentence. To constrict a sentence we need a lexicon which must have some meaning- it is the issue of semantic and words interfere within the sentence- it is the issue of syntax.
However, we do not learn only how to compose a correct sentence as an isolated unit but we learn how to use sentences in different context. A learner needs to know how to make and understand utterance which performs certain communicative acts.
Communicative grammar considers sentences in discourse groups sentences according to their meaning, not structure.
DISCOURSE can be defined as a stretch (súvislý úsek) of language consisting of several sentences which are perceived as being related in some way.
Thus in discourse sentences constitute a coherent unit (ucelená)

If we compare grammar and discourse we can say that grammar refers to the rules of language to form grammatical units such a phrase, clause and sentence. Discours, on the other hand refers to larger units of language such as paragraphes, speeches, interiews, conversations. We can say that language can be viewed in two ways:
1.as a formal system of grammatical structures
2.as a communicative systeme
When we analyze language as formal systeme, our primary unit of analysis will be the sentence or clause- central units of formal grammar.
When we analyze language as communication, an important unit of analysis is uterance.
On the level of abstraction, we can distinguish: the utterance, the sentence and the proposition/the most abstract is on this level/.
UTTERANCES occur in a contect as sounds or marks on paper. They are spoken or written by one individual to another individual, they are concrete and located in time and space.
SENTENCES on that level are much more abstract, they can exist independently of any person saying or writing them.
If they are said or written by someone they become utterances.
PROPOSITION are the most abstract, those are ideas expressed through sentences. It can be compared to the thought or ideas expressed by a sentence.

SENTENCE
Is an arrangement of words which are meaningful and grammatically correct and at the same time the words serve for communication. They can be divided from certain point of view:
minor- if they are formed in irregular way
major- if they are formed in regular way

1.MINOR SENTENCES
- they cannot be analysed into a sequence of clause elements /vetné členy/. There are only a few minor sentence types, but instances of each type are frequently used in everyday conversation and also when they are represented in fiction. They are also common in certain types of written language such as notices (No parking!), as headlines (Financial Times), as labels, advertisements ad so on. They do not follow all the rules of grammar.
The question „How do you do?“(idiomatic expression) is a minor sentence because we cannot change the person, tense without change of sense.
Some types of minor sentences look quite complex. On first impression they might be thought to be displaying a major pattern. But in each case there is something odd.
God save the queen.¬ pattern as in major sentence
Subjunctive (no saves- different meaning)
Few types of minor sentences: they can be formuled for social situations such as Hello, How do you do, Thanks, Bye. Than for example:
Interjections- Wow, Ouh
Proverbs- Out of sight, out of mind
Words and phrases in exclamations, questions,commands-Taxi! Nice day!

2.MAJOR SENTENCES
- are in vaste majority, they are sentences which can be broken down into a specific pattern of elements.
Gave a letter to Mary (subject+verb+object 1+object 2)
They can be divided into simple and multiple sentences.
Simple- is just one clause
I will never speak to her again.
Multiple- consist of more than one clause
I will never speak to her again unless she apologizes.
They can be subdivided into – compounds /priraďovacie súvetie/
Complex /podraďovacie súvetie/
We divide them according to whether the clauses are in relation of coordination /parataxis/ or subordination /hypotaxis/.
In English grammar the sentences is described as having five levels with different units:
Discourse level /celý súhrnný kontext/
Sentence level
Clause level /only 1 verb/
Phrase level /rovina fráz/
Word level /slová/

The level of phrases is an intermediate between the higher level of clauses and the lower level of words.
Phrases are seguences of words that can function as constituents or clause elements in the structure of sentences.The relation of phrases to clause elements is the relation of realization. Phrases are forms that realize clause elements. Phrases form not only syntactic units but also semantic units. They form coherent units of sense.
A noun phrase is a phrase that contains and is centered on a noun.
An adjective phrase is centered on an adjective so the head is adjective.
Eg. Short enough, extremely happy
A verb phrase consists of a verb plus all the words that follow in a simple sentence. We sometimes call it predicate.
Eg. Mary teaches two classes at harvard in the summer.
A prepositional phrase consist of a prepostion which is a chief element ans a noun phrase. Eg. In the corner of the room.
An adverb phrase consists of an adverb + its modifiers. Eg.extremely, quickly,..

A SIMPLE SENTENCE
Is the smallest sentence unit which consists of a single independant clause having two basic parts: subject and predicate.