The parts of speech in English are the categories of words based on their functions and roles within a sentence. They are the classification of all the words of a language. This classification is also known as word classes and they are the building blocks of grammar. Learning the parts of speech is a step to understanding the sentence structure.
Some grammar resources categorize the parts of speech into 8 or 10 speech parts. The most recent categorization of the parts of speech and the most commonly used one divided the parts of speech into nine categories. These nine categories are the building blocks of grammar and any sentence written or spoken in English includes words that fall into some of these parts. Each part of speech explains not what the word is, but how the word is used. Furthermore, the same word can be a noun in one sentence and a verb or adjective in another sentence according to its function in the sentence. The nine parts of speech are:

• Nouns
• Pronouns
• Verbs
• Adjectives
• Adverbs
• Prepositions
• Conjunctions
• Articles/determiners
• Interjections

1. Nouns
A noun is a word used to name a person (doctor), animal (horse), place (India), thing (card), and abstract idea (freedom). Nouns comprise the largest group of words in English (about 65%). Nouns can function in a sentence as a subject, a direct object, an indirect object, a subject complement, an object complement, an appositive, an adjective or an adverb.
The teacher explained the lesson to the students.
The manager called for a meeting.
According to the sign, Washington is 60 miles away.

2. Pronouns
A pronoun is used instead of a noun, to avoid repeating the noun. They are more generic versions of nouns that replace nouns in a sentence. Pronouns make sentences less repetitive.
The candidate who wins the greatest popular vote is not always elected.
Richard usually sends a copy of the e-mails to himself.
Mark knows the city well. He managed to meet us at the nearest shop.
Christopher was surprised to see her at the reunion.

3. Verbs
The verb is the most important part of the sentence. It asserts something about the subject of the sentence and expresses actions, events, or states of being. Verbs change form based on tense (present, past, future) and count distinction (singular or plural).
He finished the task in the evening.
Michael is a decent man. He respects his colleagues and treats everyone equally.

4. Adjectives
An adjective is a word that modifies or describes a noun or pronoun. Adjectives comprise the second largest group of words in English (about 23%). Adjectives inform about the qualities and features of people, things or concepts (big, strong, beautiful). An adjective usually precedes the noun or the pronoun which it modifies.
Mrs. Jackson papered her kitchen walls with colorful wall paper.
Many people travel to exotic places in the summer.
He was happy when he moved to his new house.

5. Adverbs
An adverb can modify a verb, an adjective, another adverb, a phrase, or a clause. An adverb indicates manner, time, place, cause, or degree and answers questions such as "how", "when", "where", "how much". Some adverbs can be identified by their characteristic "ly" suffix. Unlike an adjective, an adverb can be found in various places within the sentence.
The new typist is extremely busy.
The new couple spoke happily about their new house.
That is quite expensive.
Unfortunately, I won't be able to attend the meeting.

6. Prepositions
A preposition joins the noun, pronoun and phrases to some other part of the sentence. The word or phrase that the preposition introduces is called the object of the preposition.
She held the book over the table.
The dog is hiding under the car because it knows it will be punished for chewing up a new pair of shoes.

7. Conjunctions
A conjunction joins two words, phrases or sentences together. A conjunction indicates the nature of the relationship among the connected elements.
After she had learned to drive, Alice felt more independent.
Although the employees were tired, yet they came to the office.
Both my grandfather and my father worked in the same hospital.

8. Articles/determiners
A determiner is a word that accompanies a noun or noun phrase and determines whether it is general or specific, its quantity, relation, etc. Determiners may be treated as adjectives, instead of being a separate part of speech. There are indefinite and definite articles (a, an, the).
The teacher asked a student to answer the question.
The last section in the second test was very easy.

9. Interjections
An interjection is a word added to a sentence to convey emotion and they are usually followed by an exclamation mark. It is not grammatically related to any other part of the sentence.
Hurray! We won the game.
Oh! I am late for the office.

Words can have more than one job. That is very common in English where a word can be a verb, noun, adverb, adjective or an interjection. Check the following example:
My work permit expires in June. (The word “work” is used as an adjective)
He will have to work till midnight to deliver the report. (The word “work” is used as a verb)
Jennifer showed up for work one hour late. (The word “work” is used as a noun)

To analyze the part of speech, you should know the function of the word in the sentence. This means that you look not only at the word itself but also at its meaning, position, and use in a sentence.

Here are some parts of speech exercises to check your understanding:

1. Mr. Evans drives to work every day.
2. Jane listens to music and plays chess.
3. This car is very fast.
4. The show was fantastic.
5. He did well in the test.
6. What did she ask you to do?
7. Andy knocked on the door but nobody answered.
8. My friend said, "Oh! What a cold weather!"
9. The students listen carefully.
10. I helped him carry it.
11. We first went to the store to buy a few things.
12. They lived many miles from a new town.

Answers
1. Noun
2. Verb
3. Adjective
4. Noun
5. Adverb
6. Pronoun
7. Conjunction
8. Interjection
9. Adverb
10. Pronoun
11. Preposition
12. Article