It is a full stop, used to denote the end of a sentence. It is used when it is necessary to complete a definite statement or series of statements, before embarking upon a new statement or question.
It stands for non-breaking space -- a space between two words you want to keep on the same line when a text processing system lays out a document. Thus if you want a browser to display the name "Mr Pastry" in a single line even if the "Mr" would fit at the end of a line on the screen, you would code the HTML as "Mr Pastry". -.-.-.- I think they appear in AB, as Wraith suggests, courtesy of Word's creation of a web page.
99.9% correct booksworth. In your html, there should be a semi-colon after the "nbsp" just before the word "Pastry".
In coding any symbols like this in html there's the ampersand, something to indicate what you want to appear, "quot" for example, and then the semi-colon.