WordPress - Get current categories

index.php

<?php
var_dump( get_the_category() ); // use in wp loop
/*
object(WP_Term)#306 (16) {
  ["term_id"]=>
  int(49)
  ["name"]=>
  string(6) "Markup"
  ["slug"]=>
  string(6) "markup"
  ["term_group"]=>
  int(0)
  ["term_taxonomy_id"]=>
  int(49)
  ["taxonomy"]=>
  string(8) "category"
  ["description"]=>
  string(51) "Posts in this category test markup tags and styles."
  ["parent"]=>
  int(0)
  ["count"]=>
  int(6)
  ["filter"]=>
  string(3) "raw"
  ["cat_ID"]=>
  int(49)
  ["category_count"]=>
  int(6)
  ["category_description"]=>
  string(51) "Posts in this category test markup tags and styles."
  ["cat_name"]=>
  string(6) "Markup"
  ["category_nicename"]=>
  string(6) "markup"
  ["category_parent"]=>
  int(0)
}
*/