Your text has been cut and pasted probably from Microsoft Word. As a result it is full of garbage tags that used behind the scenes by Microsoft Office but which are not proper HTML. Several of them even throw errors, although browsers do a reasonable job of handling them.

The gaps are specifically because somebody has formated the text by using carriage returns, i.e. at the end of each paragraph hits return 2-3 times to space the text. Each of these turns into a paragraph in its own right in HTML hence the extra spacing.

The solution. Save your text first as plain text from Word and then import it.