I am confusing: ... because of "But, but "

[Purefeeling]

Hello,

I was reading a book called "Vocabulary Builder" and I notice that the letter B in the word But is written with a capital letter in this sentence:

I also thought English people would be rather shy. But most people seem very self-confident.

So could someone help me on that ... isn't the word "but" always written with a small letter because it connects two sentences that is separated with a comma.

[Yankee]

[Jamie (K)]

In school they teach children not to start sentences with words like but, because or and. It's because children have trouble learning how to write full sentences instead of fragments. Teachers find that if they forbid the kids to start a sentence with any conjunction, the kids will not write as many fragments.

In real adult life, however, many good writers start sentences with conjunctions. If you do it, though, the sentence should have all the elements of a full sentence -- subject, verb, etc.

Often the grammar rules used to teach ESL writing are similar to those taught to native English-speaking children. Adults often break these rules, but to be a good writer, you have to learn how to break them at the right times and in the right ways.

[Purefeeling]

[Purefeeling]

[Purefeeling]

I think this is the place where all learners should rely on