Parts of speech are incredibly useful tools to us as mankind, they provide the ability to communicate through text and establish philosophy and forms of verbal communication as a visual concept to glorify it and progress it farther. Some philosophers and scientists would argue the invention of written language has had a negative effect on mankind as prior to the invention of it people could memorize round-about of twenty thousand words consecutively commonly- now this is almost unheard of.
The eight primary parts of speech include adverb, conjunction, interjection, noun, participle, preposition, pronoun and verb. Each of these have very independent yet communicative distinguishing characters:
Adverbs are ultimately a verb altered from it's original state in a sentence, clause or phrase.
Conjunctions are essentially a binding part of speech describing the function of a word using one of the 'fanboys' [for, and, nor, but, or, yet, so.] For example: We were going to go to the movies, but we got there late.
Interjections are parts of speech expressing one's emotional state; i.e.: "Aha! I've found it!" 'Aha' would be an interjection in this example.
Nouns are the most well known part of speech, as it's a person, place, thing, or idea. A noun in the end is ultimately something you can name or refer to. You are a noun, and so is whatever device you're reading this from.
Participles are by definition are verbals that operate as an adjective like 'burning,' 'burying' or 'tapping.'
Prepositions are ultimately words implying relation from one thing to another for example: "The coffee is in the cup." is a sentence in which in is a preposition implying where the coffee is.
Pronoun is a noun of which lacks glorifacation. You know that the name Natalie is a proper noun, and girl is a noun, so the only way to be less descriptive while refering to something or somebody would be to use a phrase that lacks directness such as "it" "she" "him" or "her."
Verbs, lastly but not least are activities that can be done. If it can be accomplished or done it is a verb.