Make changes to node view by preprocess node
Make changes on node by hook preprocess node
<?php
function [mymoduel]_preprocess_node(&$variables) {
$node = $variables['node'];
if (module_exists('taxonomy')) {
$variables['taxonomy'] = taxonomy_link('taxonomy terms', $node);
}
...
$variables['content'] = $node->teaser;
...
// Clean up name so there are no underscores.
$variables['template_files'][] = 'node-' . $node->type;
?>