Drupal - How can I prevent a particular page being cached?

For Drupal 7:

Drupal has the function drupal_page_is_cacheable() which can be used to set a page to uncacheable.

Here is the documentation: https://api.drupal.org/api/drupal/includes!bootstrap.inc/function/drupal_page_is_cacheable/7

For Drupal 8:

// Deny any page caching on the current request.    
\Drupal::service('page_cache_kill_switch')->trigger();

Then the code is:

public function myPage() {
  \Drupal::service('page_cache_kill_switch')->trigger();
  return [
    '#markup' => time(),
  ];
}

As usual, clean your cache once done.

Disable cache for a specific page

Disable cache for a custom page from route declaration. If you want to disable cache for a custom controller (Custom module), You have no_cache option (YOUR_MODULE.routing.yml). Example : File : mymodule.routing.yml

mymodule.myroute:
  path: '/mymodule/mypage'
  defaults:
    _controller: '\Drupal\mymodule\Controller\Pages::mypage'
    _title: 'No cache page'
  requirements:
    _access: 'TRUE'
  options:
    no_cache: 'TRUE'

Added 'no_cache' route option to mark a route's responses as uncacheable

In Drupal 8, you can mention cache as max-age till you want your page ouput to be cached. For removing cache of a particular page(Controller page), write 'max-age' => 0,.

public function myPage() {
  return [
   '#markup' => time(),
   '#cache' => ['max-age' => 0,],    //Set cache for 0 seconds.
  ];
}