% symbol in python

[satishmlmlml at gmail.com]

<tr><th>key<td><input type=text name=key value="%(key)s">
rowhtml = '<tr><th>%s<td><input type=text name=%s value"%%(%s)s">\n"

what does % mean in first line of code and
what does %%(%s)s mean in second line of code

kindly explain