Every sound has onomatopoeic connotations associated with it: 'k' is a harsh, sharp sound compared to 's', which is soft & gentle (though also potentially hissing in context) by comparison. Alliteration can be used to emphasise certain phonetics in a sentence, creating the appropriate atmosphere or tone. Perhaps this is more assonance than alliteration, though...
There are other uses for alliteration, like you mentioned: the repetition of a particular starting letter emphasises that letter & consequently those words. People generally like patterns and symmetry, and a reader will often subconsciously recall recent previous words starting with that same letter, highlighting them as being on the same topic; in effect, it's like they're re-reading the words each time they come across the repeated starting letter, hence the emphasis of whatever you're saying in that sentence. Or something like that, anyway.
It depends on the words used, but generally they create a sense of snappiness and forceful nature. You can link the alliteration to the theme of the text.
hey ould give anyone tell me how to work out the effect of terminology say for example the use of colloquial and how to work out the effect of it. Because i know my terminiology but the only thing is when it comes to anotating i just don't know how to describe the effect of the terminology used.