indicates a word or phrase being defined
Used in definitions or explanations, often equivalent to 'is a ...' or 'means ...'. Follows the term being defined.
See also: というのは
'Arigatou' is a word that expresses gratitude.
used for quoting thoughts, speech, etc.
Marks quoted content, often with verbs like 言う, 思う, or 聞く. Can add contrast or emphasis to a negative statement.
See also: と
I didn't think he would come.
Emphatic version of the particle と meaning 'with'. Used to stress the companion or counterpart.
See also: と
I won't meet with him anymore.
(not) as much as; (not) so much as
Used with a negative verb to express that something is not as much as expected or not to the degree of something else.
the fact that; to think that; such a thing as
Expresses surprise, disbelief, anger, etc. about a situation. Can appear at the end of a sentence.
To think that person would do such a thing.
I never thought he was the culprit.
I've never met anyone as kind as him.
とは is a contracted, everyday form used to introduce a definition, while というのは is more explicit and formal, often used in careful explanations.
と is the plain quoting/accompaniment particle, while とは adds emphasis, contrast, or a definitional nuance on top of that basic function.
Combination of the case particle と and the topic particle は. The contraction is a natural phonetic reduction.