In certain positions in a sentence the beginnings of words undergo changes in Manx, as in all the other Celtic languages. There are three types of change:
 

(a) Lenition or Aspiration
 

(b) Nasalisation or Eclipsis
 

(c) the prefixing of h- to an initial vowel.
 
 
 
The circumstances under which each of these changes occurs are set out in the following pages, but as the occurrence of mutation in the written language is far from regular (in consequence of the uncertainty about gender and case and the number of legitimate exceptions having unsettled usage in this respect), a distinction will be made between the mutations which are regularly or almost invariably found, and those that occur less frequently.