Page 259 - Windows 10 May 2019 Update The Missing Manual: The Book That Should Have Been in the Box

UP TO SPEED DATA COMPRESSION

Data compression is the process of replacing repetitive material in a file
with shorthand symbols. For example, if a speech you’ve written

contains the phrase going forward 21 times, a compression scheme like
the one in NTFS may replace each occurrence with a single symbol,

making the file that much smaller. When you reopen the file later, the
operating system almost instantaneously restores the original, expanded
material.

The degree to which a file can be compressed depends on what kind of
data the file contains and whether it’s already been compressed by
another program. For example, programs (executable files) often shrink
by half when compressed. Bitmapped graphics like TIFF files squish

down to as little as one-seventh their original size, saving a great deal
more space. The PNG and JPEG graphics formats so popular on the

web, however, are already compressed (which is why they’re so popular
—they take relatively little time to download). As a result, they don’t
get much smaller if you try to compress them manually. That’s one of

the main rules of data compression: Data can be compressed only once.

In short, there’s no way to predict just how much disk space you’ll save
by using NTFS compression on your drives. It all depends on what you

have stored there.

Creating zipped folders

You can create a .zip archive in either of two ways:

Right-click any blank spot on the desktop or an open window.

From the shortcut menu, choose New → “Compressed (zipped)
Folder.” (Or, from the Ribbon’s Home tab, choose “New item” →
“Compressed (zipped) Folder.”) Type a name for your newly

created, empty archive, and then press Enter.