Why/When need some kind of short spelling or pronunciation?
In regular usage, nowadays we use short spellings of words in speaking or writing. For example: - They are in the cinema. => They're in the cinema. - We have been waiting for me. => We've been waiting for me. - etc... I know it makes our vocabulary and understanding easier than the real spelling of words, but my question is: why do we need that type of change and how should it be applied to our regular usage? Most importantly **when should we use this kind of short word when writing or speaking?**