Yii2 includes a handy toolbar, and built-in debugger, for faster development and debugging of your applications. The toolbar displays information
about the currently opened page, while the debugger can be used to analyze data you've previously collected (i.e., to confirm the values of variables).
By default, the debug module only works when browsing the website from localhost. If you want to use it on a remote (staging) server, add the parameter `allowedIPs` to the configuration to whitelist your IP:
By default, the trace level is automatically set to `3` if Yii is running in debug mode, as determined by the presence of the following line in your `index.php` file:
> Note: Make sure to disable debug mode in production environments since it may have a significant and adverse performance effect. Further, the debug mode may expose sensitive information to end users.
1.`init` is executed before any controller action is run. This method is the best place to attach handlers that will collect data during the controller action's execution.
2.`save` is called after controller action is executed. The data returned by this method will be stored in a data file. If nothing is returned by this method, the panel
won't be rendered.
3. The data from the data file is loaded into `$this->data`. For the toolbar, this will always represent the latest data, For the debugger, this property may be set to be read from any previous data file as well.
4. The toolbar takes its contents from `getSummary`. There, we're showing the number of view files rendered. The debugger uses