Taxonomy

Simple taxonomy autocomplete field.

Example:
$form['tagtest'] = [
  '#type' => 'entity_autocomplete',
  '#target_type' => 'taxonomy_term',
  '#title' => 'Taxonomy Term',
];

To Show more than 100 terms in taxonomy administration (overview) page, You must set the terms_per_page_admin of taxonomy.settings.

Exaple:

Example : Create a terom of the vocabulary 'test_vocabulary'

//Minimum
$term = \Drupal\taxonomy\Entity\Term::create([
          'vid' => 'test_vocabulary',
          'name' => 'My tag',
    ]);
$term->save();

Using entityQuery, you can get the taxonomy terms  of a particular vocabulary.

In drupal 8, this retrun taxonomy vocabularies as an array.

$vocabularies = \Drupal\taxonomy\Entity\Vocabulary::loadMultiple();