use of "However" in short paragraphs

Many paragraphs, such as this one, contain sentences beginning with the word "however." Seen here, "However, most major manufacturers manipulate and even create consumer demand, as anyone who watches television knows." Does this serve any particular, special function - more specifically, does "however" act as a word introducing premise, claim, conclusion, etc.? I understand that in this question the sentence following "however" serves as one of the claims on which the argument is based (answer choice "A") - I just am curious if there is any special significance behind the usage of "however." Thanks in advance.