What is used at the beginning of words to create alliteration?

The beginning of words, where alliteration takes place, is called the initial consonant sound.

While it's technically the sound that matters, we often refer to it as the first letter for simplicity.

For example:

* Peter picked a peach. (The "p" sound is repeated)

* She sells seashells by the seashore. (The "s" sound is repeated)

Remember, alliteration is about the sound, not necessarily the exact spelling.