What is a noun?

noun (noun): a word (except a pronoun) that identifies a person, place or thing, or names one of them (proper noun)

The simple definition is: a person, place or thing. Here are some examples:

• person: man, woman, teacher, John, Mary
• place: home, office, town, countryside, America
• thing: table, car, banana, money, music, love, dog, monkey. The problem with the simple definition above is that it does not explain why "love" is a noun but can also be a verb.

Another (more complicated) way of recognizing a noun is by its:

1. ending
2. position
3. function

1. Noun ending

There are certain word endings that show that a word is a noun, for example:

• -ity → nationality
• -ment → appointment
• -ness → happiness
• -ation → relation
• -hood → childhood

But this is not true for the word endings of all nouns. For example, the noun "spoonful" ends in -ful, but the adjective "careful" also ends in -ful.

2. Position in sentence

We can often recognise a noun by its position in the sentence.
Nouns often come after a determiner (a determiner is a word like a, an, the, this, my, such):

• a relief
• an afternoon
• the doctor
• this word
• my house
• such stupidity

Nouns often come after one or more adjectives:

• a great relief
• a peaceful afternoon
• the tall, Indian doctor
• this difficult word
• my brown and white house
• such crass stupidity

3. Function in a sentence

Nouns have certain functions (jobs) in a sentence, for example:

• subject of verb: Doctors work hard.
• object of verb: He likes coffee.
• subject and object of verb: Teachers teach students.

But the subject or object of a sentence is not always a noun. It could be a pronoun or a phrase. In the sentence "My doctor works hard", the noun is "doctor" but the subject is "My doctor".

What is tense?

tense (noun): a verb-based method used to indicate the time, and sometimes the continuation or completeness, of an action or state in relation to the time of speaking. ORIGIN Latin tempus "time"

The concept of tense in English is a method that we use to refer to time - past, present and future. Many languages use tense to talk about time. Other languages have no concept of tense at all, but of course they can still talk about time, using different methods.

So, we talk about time in English with tense. But, and this is a very big but:

• we can also talk about time without using tense (for example, going to is a special construction to talk about the future, it is not a tense)
• one tense does not always talk about one time (for example, we can use the present tense, or even the past tense, to talk about the future )

We cannot talk of tenses without considering two components of many English tenses: time andaspect. In simple terms...

Time expresses:

• past - before now
• present - now, or any time that includes now
• future - after now

Aspect can be:

• progressive - uncompleted action
• perfective - completed action or state

The following table shows how these components work together to create some basic tenses.

		time
		past	present	future
simple (no aspect)		sang	sings	will sing
aspect	progressive	was singing	is singing	will be singing
	perfective	had sung	has sung	will have sung

(Some say that simple tenses have "simple aspect", but strictly speaking simple tenses are simply unmarked for aspect.)

The progressive aspect produces progressive or "continuous" tenses: past continuous, present continuous, future continuous.

The perfective aspect produces perfect tenses: past perfect, present perfect, future perfect.

And the two aspects can be combined to produce perfect continuous tenses: past perfect continuous, present perfect continuous, future perfect continuous.

What is a verb?

The verb is king in English. The shortest sentence contains a verb. You can make a one-word sentence with a verb, for example: "Stop!" You cannot make a one-word sentence with any other type of word.

Verbs are sometimes described as "action words". This is partly true. Many verbs give the idea of action, of "doing" something. For example, words like run, fight, do and workall convey action.

But some verbs do not give the idea of action; they give the idea of existence, of state, of "being". For example, verbs like be, exist, seem and belong all convey state.

A verb always has a subject. (In the sentence "John speaks English", John is the subject and speaks is the verb.) In simple terms, therefore, we can say that verbs are words that tell us what a subject does or is; they describe:

• action (Ram plays football.)
• state (Anthony seems kind.)

There is something very special about verbs in English. Most other words (adjectives, adverbs, prepositions etc) do not change in form (although nouns can have singular and plural forms). But almost all verbs change in form. For example, the verb to work has five forms:

• to work, work, works, worked, working

Of course, this is still very few forms compared to some languages which may have thirty or more forms for a single verb.

https://www.englishclub.com/grammar/verb-what.htm