How the Grails Link element work

Here are some examples:

<g:link action="show" id="1">Book 1</g:link>

<g:link action="show" id="${currentBook.id}">${currentBook.name}</g:link>

<g:link controller="book">Book Home</g:link>

<g:link controller="book" action="list">Book List</g:link>

<g:link url="[action:'list',controller:'book']">Book List</g:link>

<g:link action="list" params="[sort:'title',order:'asc',author:currentBook.author]">

Book List

</g:link>