Question: What is prepping data? 

Prepping data function helps us to prep the data before use apply rules to it. We can use various prepping function that are:
Xss_clean
Prep_for_form
Prep_url
Strip_image_tags
Encode_php_pags

Question:Define delimiter. 

A delimiter is a sequence of one or more characters used to specify the boundary between separate, independent regions in plain text or other data streams. An example of a delimiter is the comma character, which acts as a field delimiter in a sequence of comma-separated values.

Question:What is callback? 

 A callback is simply a function in your controller code that is used in place,or along with, a rule.

Question:What is method chaining? 

Method chaining enables us to vastly simplify the syntax by connecting multiple functions. Example:
$this->db->select(‘name,email’)->from(‘users’)->where(‘id’,5)->limit(10,20);

Question:What are dashboard functions? 

Dashboard function gives us a small problem to overcome. We want to be able to call this function from other functions in the class, as we have in the index function.

Question:What are parse functions? 

Usually parse functions convert the data from one type into another type. Example: string to number, number to string.

Question:What are debug functions? 

We should add in a debug function for ease of use. When  the  debug  function  is called , we want  to  echo  out  the  URL  of  the  last  API  call , and  the  HTTP  Status  Code.

Question:Define hooks in term of codeigniter? 

A CodeIgniter hooks feature provides a means to tap into and modify the inner workings of the Codeigniter framework without hacking the core files. The hooks features can be globally enabled/disabled by—
                                $config [‘enable hooks’] =TRUE;

Question:What is thumbnail? 

The thumbnail function will simply resize the original image to smaller so that the browsers are capable to load it fast as an icon.
$this->image_lib->resize();

Question:Why we use _remap() ? 

If controller contains a function named _remap(), it will always get called regardless of what URI contains. It overrides the normal behavior in which the URI determines which function is called, allowing us to define our own function routing rules.