Make UNIX directory trees in a single swipe

Defining directory trees individually [BAD Practice]
Create tmp/a/b/c
~ $ mkdir tmp
~ $ cd tmp
~/tmp $ mkdir a
~/tmp $ cd a
 ~/tmp/a $ mkdir b
~/tmp/a $ cd b
~/tmp/a/b/ $ mkdir c
~/tmp/a/b/ $ cd c
          ~/tmp/a/b/c $

Defining directory trees with one command [good Practice]
~ $ mkdir -p tmp/a/b/c

Another example,              
~ $ mkdir -p project/{lib/ext,bin,src,doc/{html,info,pdf},demo/stat/a}