Consonant, Vowel and Difthong

Consonant

Consonant is a speech sound that is articulated with complete or closure of the vocal tract. to avoid the ambiguous sound, you should learn IPA (International Phonetic Alphabet)

There are 21 consonants letters in English with 24 consonants sounds in most of English. I didn't learn linguistic deeply.

Beside the consonant letters, as miss +Santi Awati​​ had said, the sound "th", "ch" are also consonant for a single sound.
And letter "x" has two consonants sound which is "ks"

Vowel 

Vowel is a speech sound in which the mouth is open and the tongue is not touching the top of the mouth, the teeth.eg: a,i,u,o, e, The letter "Y" can be both consonant and vowel. In the word "yellow" the "y" is a consonant, but in the word happy, the "y" is a vowel.

Difthong

difthong as I have asked to my master mr +Anton Ardyanto​​ had said. That difthong is the sound which you pronounce as 2 vowels. There are many difthong in English linguistic, such as :

ei : rate, may, say, afraid, remain
The letter "a" is difthong as it pronounce as "ei".

ai : combine, arrive, smile
The letter "i" is diftong as it pronounce as "ai"

au : how, cow, browser
The letter "ow" is difthong as it pronounce as "au".

oi : joy, toy, loyal, destroy
The letter "oy" is difthong as it pronounce as "oi".

The important thing you should remember about difthong is, that is the way you pronounce, not the way its written.