Semivowel

A semivowel is a sound that acts as both a vowel and a consonant. The two main semivowels in English, /w/ and /j/, as in wet and yet, are known as "glides", but there are others, such as /r/ and /l/, known as "liquids".

Glides
Glides occur before or between vocalic nuclei.

As /w/

 * what - west - war;
 * way;

As /j/

 * yacht - yes - your;
 * music;

Liquids
Liquids occur after vocalic nuclei and before consonants.

As /r/

 * car

As /l/

 * full - pool