+Unlike ZIP files, WIM files can contain multiple independent toplevel directory
+trees known as images. While each image has its own metadata describing a
+directory tree and file access modes, files are not duplicated for each image;
+instead, each file is included only once in the entire WIM. Microsoft did this
+so that in one WIM file, they could do things like have 5 different versions of
+Windows that are almost exactly the same.
+
+Microsoft provides documentation for the WIM file format, XPRESS compression
+format, and LZX compression format. The XPRESS documentation is acceptable, but
+the LZX documentation is not entirely correct, and the WIM documentation itself
+is incomplete.
+
+A WIM file may be either stand-alone or split into multiple parts.
+
+ PROGRAMS
+
+wimlib provides a public API for other programs to use, but also comes with two
+programs: `imagex' and `mkwinpeimg'.
+
+`imagex' is intended to be like the imagex.exe program from Windows. `imagex'
+can be used to create, extract, and mount WIM files. Both read-only and
+read-write mounts are supported. See the man page `doc/imagex.1' for more
+details.
+
+`mkwinpeimg' is shell script that makes it easy to create a customized bootable
+image of Windows PE that can be put on a CD or USB drive, or published on a
+server for PXE booting. See the main page `doc/mkwinpeimg.1' for more details.
+
+There is an additional program, `wimapply', that is not installed by default.
+It can be used to build a small executable with the ability to apply a WIM image
+from a standalone WIM, without having to build the whole shared library. This
+could be useful on Linux boot clients that only need to be able to apply a WIM,
+not capture/split/join/append/export/mount a WIM. See `programs/wimapply.c'.
+
+ COMPRESSION RATIO
+
+wimlib can create XPRESS or LZX compressed WIM archives. Currently, the XPRESS
+compression ratio is slightly better than that provided by Microsoft's software,
+while the LZX compression ratio is approaching that of Microsoft's software but
+is not quite there yet. Running time is as good as or better than Microsoft's
+software, especially with multithreaded compression, available in wimlib v1.1.0
+and later.
+
+The following tables compare the compression ratio and performance for creating
+a compressed Windows PE image (disk usage of about 524 MB, uncompressed WIM size
+361 MB):
+
+ Table 1. WIM size
+
+ XPRESS Compression LZX Compression
+ wimlib imagex (v1.2.1): 138,971,353 bytes 131,379,943 bytes
+ Microsoft imagex.exe: 140,406,981 bytes 127,249,176 bytes
+
+ Table 2. Time to create WIM
+
+ XPRESS Compression LZX Compression
+ wimlib imagex (v1.2.1, 2 threads): 11 sec 17 sec
+ Microsoft imagex.exe: 25 sec 89 sec