In almost all reading devices, users can change the font size.  In the Kindle, the font can be changed from the default size of 3 down to the smallest size of 1 and the largest size of 8.   (See our the screenshots of an example ePUB in this micro-article FAQ: Text reflows--or wraps.

In many ereading devices, the human reader can even change the font style.  This will also affect how the book looks, not only in the font.  This will change the spacing between letters and words, changing your book yet again.  For this example, we thank Connie Pontious, author of the charming children's book, "Sharon and Eleanor," for allowing us to use her lovely work for our  example.    ("Sharon and Eleanor" is available on Kindle by clicking here.)  These screenshots were all taken from an actual Nook device.  Top row left:  The book with "Ascender Sans" font chosen, default size; Top row, right:  The book with "Georgia" font chosen, default size.  Second row, left:  the title with Georgia font, smallest possible font size; Second row, right; the same page, also with Georgia, using one of the largest font sizes available. 

Sharon and Eleanor, on a Nook, with Ascender Sans Font chosen
Sharon and Eleanor, on a Nook, with Ascender Sans Font chosen
Sharon and Eleanor, still on the same Nook, now with the default-size Georgia chosen by the reader.
Sharon and Eleanor, still on the same Nook, now with the default-size Georgia chosen by the reader.
Sharon and Eleanor, on the same Nook, now with the Georgia font size set much, much smaller.
Sharon and Eleanor, on the same Nook, now with the Georgia font size set much, much smaller.

 

What's important to remember, when you view the above images (you can click any of them to launch them in a lightbox), is this:  

...this is exactly the same book, on the same device. The only thing that's changed is that the person reading it has chosen a different default font to read it with, or a different font size.  That's why making eBooks is so tricky--the person who formats them has to be able to ensure that no matter what your reader does, the book will still work, function, and read properly, despite the reader's choices.  

T'was the Night Before Christmas... 

 (With apologies to Clement Clarke Moore, may he forgive my doggerel...)

...and all through the shop,
all we minions were working,
   until ready to drop.

The ebooks were flying,
the covers were spare,
The edits were crazy,
   with "one more thing I must share!"

We waited for Santa,
'Cuz we love old Saint Nick,
But Hitch made us work,
   Waving 'round an old stick!

So slave we all did,
And made all your books,
So that Hitch would say now,
   that we're off the hook.

Come today we're off,
to rest up our fingers,
Our hats we will doff,
   No books they do linger.

But we'll all be back,
Don't give it a thought,
for like all wage slaves,
   we're easily bought.

We'll be back on the fifth,
all eager and fresh,
All ready for you,
   after a well-deserved rest.

So Hitch wants to say,
very strongly and loud,
THANKS ALL YOU GUYS,
  you're the best type of crowd.

Indy and Len and Hitch and the gang,
will be back on the 5th,
to do books with a BANG!

In the meantime don't worry,
if you're in a hurry,
'cuz some poor guy got stuck
   sitting here like a duck.

Your emails we'll receive,
so no need to grieve.
We'll be a bit slow,
but we're raring to go.

Your books will be worked on,
your edits still made,
we're just resting a bit,
   before we all fade.

So please excuse the delays;
It won't be for days;
we'll jump on your queries,
   for your wondrous new series.

We waited for Santa,
'Cuz we love old St. Nick,
And sure 'nuff he came,
   It wasn't a trick.

And as he rode off,
into the night,
I could swear I heard Hitch yell,
   "That Edit's Not Right!"

~~~~~~~~~~

We'll be back on the morning of January 5th; we'll be here parttime between now and then, thanks.