<cfparam> tag creates a variable if it does not already exist. You can assign a default value using the
default attribute. This can be used if you want to create a variable, but don't want to overwrite it if it has been previously created elsewhere.
Here the variable hasn't been set previously, so it will be assigned with the
<cfparam name="firstName" default="Justin"> <cfoutput> Hello #firstName# </cfoutput>
Here the variable has already been assigned using the
<cfset> tag, so this value will override the default value in the
<cfset firstname="Justin"> <cfparam name="firstName" default="Barney"> <cfoutput> Hello #firstName# </cfoutput>