What the 1st method that is fired during the page load?

The first stage in the page lifecycle is the initialization. This stage is characterized by the Init event, which fires to the application after the page's control tree has been successfully created. In other words, when the Init event arrives, all the controls statically declared in the .aspx source file have been instantiated and hold their default values. Controls can hook up the Init event to initialize any settings that will be needed during the lifetime of the incoming Web request. For example, at this time controls can load external template files or set up the handler for the events. You should notice that no view state information is available for use yet.