The post thumbnail
<?php // IN FUNCTIONS.PHP
if ( function_exists( 'add_image_size' ) ) {
add_theme_support( 'post-thumbnails', 120, 90, true );
add_image_size( 'home_post', 215, 172, true );
add_image_size( 'director', 280, 280, true );
add_image_size( 'member', 160, 160, true );
add_image_size( 'resource_thumb', 562, 380, true );
add_image_size( 'news_thumb', 562, 380, true );
add_image_size( 'student_thumb', 160, 160, true );
}
// IN PAGE TEMPLATES:
<?php the_post_thumbnail('research_thumb', array('class' => 'img-responsive')); ?>