This section explains any preliminary work that you may need to do before beginning work on the task.

This section lists the steps required in order to complete the task.

This section explains how the steps performed in the previous section allows us to complete the task. This section is mandatory.

This section provides some extra information relevant to the task.

You will also find a number of styles of text that distinguish between different kinds of information. Here are some examples of these styles, and an explanation of their meaning.

Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "We will go through the important features of the pygame module, which is necessary to build our arcade game, including playing sounds and controlling the menu."

A block of code is set as follows:

GPIO.output(25, True) 
while 1:
   GPIO.output(25,False)
   sleep(1)
   GPIO.output(25,True)
   sleep(1)

Any command-line input or output is written as follows:

# cp /usr/src/asterisk-addons/configs/cdr_mysql.conf.sample
     /etc/asterisk/cdr_mysql.conf

New terms and important words are shown in bold. Words that you see on the screen, in menus or dialog boxes for example, appear in the text like this: "clicking the Next button moves you to the next screen".