As children progress in their literacy development, they move from the broader areas of phonological awareness to the narrower ones. First, they learn to recognize rhyme and alliteration and to hear words in sentences and syllables in words. Once children have achieved word and syllable awareness, they can focus their attention on the smaller parts within the syllable. At first, this means dividing one-syllable words into onsets and rimes. The onset is the initial consonant or consonant cluster of the word, and the rime is the vowel and consonants that follow it. For example, in the word bat, b- is the onset, and -at is the rime. In swim, sw- is the onset, and -im is the rime. The final area of phonological awareness - and the most critical for reading and writing - is phonemic awareness. Phonemic awareness is the ability to hear, identify, and manipulate the individual sounds in spoken words. It is necessary to learn to read in an alphabetic written language system. In order for children to benefit from phonics instruction, they must be able to pay attention to phonemes.