Short answers, pulled from the story.
A vowel is a speech sound produced without any constriction in the vocal tract, while consonants involve a constriction or closure at some point along the vocal tract. Phonologically, vowels form the peak or nucleus of a syllable, whereas consonants typically form the onset and coda.
The word vowel comes from the Latin word vocalis, meaning "vocal" or relating to the voice.
The cardinal vowel system was developed by Daniel Jones to describe vowels in terms of three articulatory features: tongue height, tongue backness, and lip roundedness. These three parameters are mapped in the schematic quadrilateral IPA vowel diagram.
It is not straightforward to identify a single language with the most vowels, because long vowels, nasal vowels, and different phonation types may or may not be counted separately. Standard Danish has eleven to thirteen short vowels, the Amstetten dialect of Bavarian has thirteen long vowels, and the Jinhui dialect of Wu Chinese has eleven basic vowels plus a restricted vowel and seven nasal vowels.
Yes. In Nuxalk, a language of the American Pacific Northwest, scs means "seal fat" and consists entirely of consonants. Czech allows whole tongue-twister sentences built from syllabic consonants, and the Miyako language of Japan has words such as ss for "dust" that contain no voiced sounds at all.
The Great Vowel Shift was a series of dramatic changes in the pronunciation of English vowel phonemes that occurred after printing was introduced to England and spelling was largely standardized. Because the spelling system was not updated to reflect these pronunciation changes, English developed numerous inconsistencies between how vowels are spelled and how they are pronounced.