This area of study is very important indeed to all English Language and English Language and Literature specifications. Although you will need to understand the two terms primarily because they refer to spoken English, there are other reasons to become familiar with them in written contexts.
Some people have very noticeable ways of pronouncing certain sounds.
This is a feature of his 'idiolect' , his personal speech pattern, but not part of his accent. Please note that this term is not insulting - we all have an idiolect. It's sometimes suggested that the British are particularly concerned with matters of accent, though studies suggest that people everywhere are keen to judge others by the sound of their voice. Work through this unit by clicking on the large arrows, or jump to a section by clicking on the small arrows. See how Dickens uses this to great effect in Hard Times - English TV Programme 2.