AIML stands for Artificial Intelligence Markup Language. It's an XML-based language designed by Dr. Richard Wallace in 2001 for development of the A.L.I.C.E. chatbot.
<aiml version="1.0">
<!-- Basic atomic trigger/response -->
<category>
<pattern>HELLO BOT</pattern>
<template>
Hello, human.
</template>
</category>
<!-- Wildcard, variable learning, random replies. -->
<category>
<pattern>MY NAME IS *</pattern>
<template>
<think><set name="name"><formal/></set></think>
<random>
<li>It's nice to meet you, <get name="name"/>.</li>
<li>Nice to meet you, <get name="name"/>.</li>
</random>
</template>
</category>
<!-- Redirect (alias) one pattern to another. -->
<category>
<pattern>CALL ME *</pattern>
<template>
<srai>MY NAME IS <star index="1"/></srai>
</template>
</category>
<!-- Conditions -->
<category>
<pattern>WHAT IS MY NAME</pattern>
<template>
<condition name="name">
<li value="undefined">You never told me your name.</li>
<li>Your name is <get name="name"/>, seeker!</li>
</condition>
</template>
</category>
</aiml>
See RiveScript vs. AIML for the language and syntax differences between RiveScript and AIML.