These are valuable alternatives to using the mouse - which many people overuse. Especially when your hands are already at the keyboard, using the mouse can mean unnecessary movement, over-exertion of the fingers and arm - and wasted time.
Many selection operations with the mouse cause undue tension in the hand and fingers. This is the case for detailed positioning of the cursor, such as at the exact beginning of a sentence. You will find that some of these commands are easier to use than the mouse.
This is not to say that the mouse should not be used, but only when it is the easiest and least stressful. Knowing all options, you can choose what is best at a given moment - and what fits your personal work style.
There are many more shortcuts and hand-saving functions than are listed here, but these are among the most powerful. The Microsoft Word manual details even more options, including more detailed tools with great efficiency and hand-saving power - such as the use of Style Sheets for automatic formatting. You are encouraged to explore.
Shift-Arrow Keys
Holding down the Shift key while pressing the right or left arrow key, individual characters will be selected or de-selected depending on their current selection status. Pressing the up or down arrow key simultaneous with the Shift key will select one line of text at a time, from the insertion point.
Command - Shift-Arrow Keys
Pressing the left or right arrow keys while holding down both Command and Shift keys will select or de-select one word at a time. Punctuation is treated as a word. Pressing the up or down arrow key will select one paragraph at a time.
Command - Mouse Click
Click the mouse button while the cursor is over any point in a sentence and the entire sentence will be selected.
Triple-Click
Pressing the mouse button three times in sequence will select an entire paragraph, from hard return to hard return. It is not necessary to rush the three clicks.
Tab/Shift-Tab
These keys will move forward/backward sequentially through entry spaces in dialog boxes. The space will be automatically highlighted, so any existing text will be deleted with the first keystroke.
Command - First Letter
In a dialog box, pressing the Command key simultaneously with the first letter of a radio button or check box choice will select/de-select that choice.
Numeric Keypad
Pressing "7" will move the cursor to the beginning of the line, "1" will move to the end. Using the Command key with these will move to the beginning or end of a sentence. The Num Lock function must be off for these to work.
View Menu: Ruler (Command - R)
View Menu: Ribbon (Command - Option-R)
These two items toggle the appearance of the ruler and font control bars at the top of the window. When both are appearing - particularly on smaller computer screens - they occupy enough vertical "real estate" so as to demand additional mouse work to scroll the pages. These commands allow you to bring them into view as you need them, and then remove them to optimize the amount of your document you can see.
Tool Menu: Preferences: Toolbar (Icon): Customize
The Toolbar is the set of icons that appears at the top of the screen as a default position. This can be customized for any menu function, and many dialog box choices. Rather than open windows or drag and click on menus, a single click can initiate the functions you use most often. This dialog box allows you to choose the function and the icon to represent it on the toolbar. You may also choose the location. Putting the Toolbar to the side will increase the amount of visible text and therefore reduce scrolling.
Format Menu: Paragraph: Before/After
Enter an amount for automatic spacing before or after a paragraph. Many users press the Return key a second time to create space between paragraphs. This function saves the extra keystroke, and also makes the Command-Shift-Down/Up Arrow (moves a paragraph at a time) function listed here more useful.
Text Formatting
Bold = Command -B
Left-Align = Command - Shift-L
Italic = Command - I
Right Align = Command - Shift-R
All Caps = Command - Shift-K
Center Align = Command - Shift-C