The Boston accent is one of the most famous accents in the United States. President John F. Kennedy spoke with the Boston accent. The two features which are most associated with the Boston accent are features which vary from speaker to speaker. They are the lack of rhoticity and the broad a.
The non-rhotic pronunciation of the Boston accent is also heard in New York and other parts of New England. In Canada, this pronunciation occurs in the southern part of Nova Scotia. Words such as "father" and "card" do not preserve the r that is heard in other American accents. However, it is important to note that not all people from Boston have a non-rhotic pronunciation. Some have a rhotic pronunciation and in other speakers, rhoticity is variable.
For non-rhotic speakers, the words "heart" and "hot" are pronounced differently. The first word has the low back unrounded vowel of "father" and the second has the low back rounded vowel which is also heard in Received Pronunciation. This is different from New York where the two words are pronounced the same.
The broad a is also associated with the Boston accent. However, it is used less extensively than in Received Pronunciation. Words such as bath, ask and answer are often pronounced with this vowel. Other American accents only use the low front vowel of cat in these words. Though the broad a is a feature of the Boston accent, many Boston speakers do not use it. The word aunt is a notable exception. All speakers of the Boston accent pronounce the word aunt with a low back vowel.
The Boston accent is one of the most recognized accents of the United States. It is a prestigious accent with two features which it shares with Received Pronunciation. They are the broad a and the lack of rhoticity.