How start and end PHP session using <a> link?

[stangasm]

How can I start and end session using links? Have some links 'Cat', 'Rat', 'Cow' etc. If clicks on "Cat" want to start a session. (There are so many sub divisions inside "cat" page ) Then after some time clicks on "Cow" link, want to end the previous "Cat" session and start new session for "Cow". Is this possible? Please extend your help.I am tried these much:If selects cat want to get the content "cat".\[code\] <a href="http://stackoverflow.com/questions/12797209/Cat.php?animal=cat">Cat</a>\[/code\](in this case I am getting the content "cat" only in "Cat.php").And in Cat.php\[code\] <?= $_GET['animal']; ?> \[/code\]