presidency of drupal template file I am new to drupal themeing, I have tried to find the presidency of template files(.tpl.php).. So my question is for a particular scenario if I have html.tpl.php, page.tpl.php, block.tpl.php, node.tpl.php, taxonomy-term.tpl.php, template.php, 


which file going to run first?
if I want to make change some variable's value for page.tpl.php/html.tpl.php then I need to write a function XXX_preprocess_page()/XXX_preprocess_html() according to this listed presidency (https://api.drupal.org/api/drupal/includes!theme.inc/function/theme/7) ?
Answer 1:-template.php file will runs first.you can check it by using die() on top of all files.

answer2 :-For changing some variable's value for page.tpl.php/html.tpl.php use function function XXX_preprocess_page().

html.tpl.php -> Handles meta info, body classes 

page.tpl.php -> Handles content body display

node.tpl.php -> Handles content display

field.tpl.php ->Handles per field display

Template.php provide display alteration  for all these files.