To select a single word double click anywhere in the word.
To select a complete sentence ctrl click anywhere in the sentence.
To select an entire paragraph triple click anywhere in the paragraph.
To select a block of text click at the start of the block of test to be selected and then shift click at the end of the block.
To select the entire document use ctrl A.
To extend any selection hold down the shift key and then use the arrow keys to extend the selection one character or line at a time, page up and page down to extend the selection one page at a time, or home or end to extend the selection to the top or bottom of the document.
This article written by Stephen Chapman, Felgall Pty Ltd.