How to get id, name and slug on wordpress

on page

page.php

Get category slug by ID

$category = get_category( $category_ID );
echo $category->slug;

Get category ID by slug

$idObj = get_category_by_slug( $cateslug );
$categoryID = $idObj->term_id;

Get tag name by ID

echo get_term_by('id' ,ここにタグID,  'post_tag')->name;

Get tag name by slug

$tag = get_term_by('slug', ここにタグスラッグ, 'post_tag');
echo $tag->name;

on category

category.php

Get category ID

$getcategory = get_category( get_query_var( 'cat' ) );
$cateid = $getcategory->cat_ID;

Get parent category ID

$cateid = get_query_var( 'cat' );//現在のカテゴリID
$child = get_category($cateid);
$parentID = $child->parent;//親カテゴリのID

Get category name

echo get_queried_object()->name;

single_cat_title('' , true );

on tag

tag.php

Get tag id

$tag_id = get_query_var('tag_id');

Anywhere

Get post id by url

$postid = url_to_postid( $url );