Permalinks

echo get_permalink(18);
echo get_permalink($post->ID);
echo "<a href=" . get_permalink( $post->ID ) . " rel='bookmark'>";

<a href="<?php echo get_permalink( $post->ID ); ?>" rel='bookmark'>

bloginfo('url'); //home
bloginfo('name'); //blogtitel of websitetitel of Site Titel of Site Title
bloginfo('template_directory');
bloginfo('description'); //Slogan of Tagline