How to detect when a user navigates to a taxonomy term page and access that terms data?
Since there is no global variable that you could use to load the node, you will have to use code like the following:

&lt;?php
if ( arg(0) == 'node' &amp;&amp; is_numeric(arg(1)) &amp;&amp; ! arg(2) ) {
$node = node_load(arg(1));
}
dsm(get_defined_vars());
?&gt;


The dsm(get_defined_vars()); part is of course optional and will only work if you have the devel module enabled. However, if you do have devel, you will be able to see the whole $node object and the tags associated with the specific node.

Notice, that if you are in a term page, you can use the same principle to load a specific term. For example:

&lt;?php
if ( arg(0) == 'tag' &amp;&amp; is_numeric(arg(1)) &amp;&amp; ! arg(2) ) {
$term = taxonomy_term_load(arg(1));
}
dsm(get_defined_vars());
?&gt;