PDF is a file format which allows the exchange of complex formatted documents among many users, independent of the details of hardware platform or word processor software on any local computer.  It is an outgrowth of software originally developed to make computer generated documents directly readable by commercial printing equipment.  Download and installation of the FREE Adobe Acrobat Reader software now makes it possible for just about any web connected computer to read .pdf files on their local screen, and to produce printable versions including graphic information..

    Since PDF was originally designed pretty much to generate a "book", one commonly searches for information in .pdf files by the same techniques one would use with a book -- look up a page number in the Index or in the Table of Contents, or else just browse from page to page.  Modern versions of Acrobat are even more sophisticated, so that .pdf documents with internal hyperlinks are now common..

    Here are some handy tricks with acrobat reader that might be helpful in navigating through .pdf documents.

    1.  The "Grabbing Hand" -- Acrobat commonly loads with a single page displayed on screen, and with the cursor in the form of an open hand.  Pressing the mouse button will cause the hand to close, allowing the page to be dragged around the screen.

    2.  The top tool bar -- Icons across the top of the screen have reasonably familiar shapes, and are provided with popups to describe their purpose when pointed to with the mouse.  The icon for the currently active cursor mode (probably the hand) will be highlighted.  The magnifying glass cursor provides dynamic zoom capability -- just activate that cursor, position the magnifier at the center of the area of interest, and use left click to magnify or right click to reduce.  There are also several buttons on this toolbar to rapidly change the magnification (full sized -- fit screen width -- fit in screen) without changing cursors.  The binoculars icon activates a search feature to seek specific words or phrases.

    3.  The bottom bars -- Here are information readouts including the actual dimensions of the printable area, and the number of the page currently being displayed.  Here also are some triangle and arrow icons, for moving forward and back through the document -- either page by page in sequence, or view by view (this latter more like browser "forward" and "back" operations).   To go directly to a specific page, just type the desired number into the current-page display field.  So, for example, suppose while reading the table of contents on page 2 you decide you want to go to page 8.   Just overtype 8 in place of 2 in the current-page display box, hit "Enter" on your keyboard, and there you are.  NOW pressing the "Previous page" triangle will take you to page 7, but pressing the "Previous View" arrow will take you back to page 2.
    The group of rectangular icons at the right end of this bar control whether single or facing pages are displayed, with or without continuous vertical scrolling across page boundaries.

    4.  The main Scroll Bar -- Acrobat does not do real-time scrolling as one drags the scroll box along the bar.  Instead, it provides a pop-up display showing the target page number that will be centered in the window if the mouse button is released at its current position.  Thus, to find page 16 (for example) simply drag the scroll box in the appropriate direction until the pop-up shows number 16, and then release the mouse button.

     SO -- one basic navigation technique for .pdf files is to search the table of contents in the early pages, or else scroll quickly to the end of the document to locate the index, and look up the appropriate page number for the topic of interest.  Then use this pop-up display on the scroll bar to move quickly to the desired page.

    5. The navigation screen -- Through all of this, you may have been seeing a document that fills the full width of your screen, or you might have the document in a window on the right hand side, with a narrower window open along the left edge -- depending on startup settings in your Acrobat Reader and in the file being viewed.  Press the small icon in the lower-left corner (the icon that looks like two triangles, back to back, with a vertical line between -- like the "open doors" button in an elevator) to open and close the left-hand window.  This narrow window is the navigation screen.  Note that the document magnification automatically changes to fit exactly the same view of the page into the new document width as the navigation screen is opened and closed.
    There are several tabs along the edge of the navigation screen.  In a full-featured .pdf document, all of these tabs might contain useful information.  The bookmarks screen might be blank OR it might contain an abbreviated table of contents, with live hyperlinks to jump directly to some desired section of the document (like the index, for instance).