Here is the list of Important wordpress Functions, these functions are used in almost our areas of wordpress app development, You can bookmark this list for future use.
// Includes header.php
get_header()
// Includes footer.php
get_footer()
// checks if posts present
have_posts()
// displays title
the_title()
// Display some content using excerpt
the_excerpt()
// displays content
the_content()
// Check if is front page
is_front_page()
// checks which page
is_page(pass page id or page slug here)
// Used in links (Makes title a link by getting url)
the_permalink()
// For navigation link display
wp_nav_menu()
// Gets home page url
home_url()
// gets site name and description
bloginfo('name')
bloginfo('description')
// Gets pages list
wp_list_pages()
// Get title from post id
get_the_title(pass post id here)
// Get permalink using page id
get_the_permalink( id goes here)
// Get the time
the_time('d/m/y')
// Get the post author name in loop
the_author()
// Get the author posts url in loop
get_author_posts_url(pass author id here)
// Get author id in loop
get_the_author_meta('ID')
// Get categories array
get_the_category()
// get category link for making link in loop
get_category_link(pass category id here)
// check if is category archive, on archive page using this function
is_category()
// check if is tag archive, on archive page using this function
is_tag()
// check if is author archive, on archive page using this function
is_author()
// check if is day archive, on archive page using this function
is_day()
// check if is month archive, on archive page using this function
is_month()
// check if is year archive, on archive page using this function
is_year()
// Check if post has thumbvnail
has_post_thumbnail();
//Show user search term they entered on search.php using
the_search_query()