There are a number of text conventions used throughout this book.

CodeInText: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: "Many organizations might have applications that will be listening on a port that is not part of the nmap-services file."

A block of code is set as follows:

<?php 
  if(!empty($_GET['k'])) { 
    $file = fopen('keys.txt', 'a'); 
    fwrite($file, $_GET['k']); 
    fclose($file); 
  } 
?> 

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

<?php 
  if(!empty($_GET['k'])) { 
    $file = fopen('keys.txt', 'a'); 
    fwrite($file, $_GET['k']); 
    fclose($file); 
  } 
?> 

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

python -m SimpleHttpServer 8000  

Bold: Indicates a new term, an important word, or words that you see onscreen. For example, words in menus or dialog boxes appear in the text like this. Here is an example: "If you go to the Logs tab inside Current Browser, you will see that the hook registers everything the user does in the browser, from clicks and keystrokes to changes of windows or tabs."