You can define your own variables to use in AWK programming, as with any programming language.
You can define the variable using any text, but it MUST not start with numbers:
$ awk '
BEGIN{
var="Welcome to AWk programming"
print var
}'
You can define any type of variables and use it the same way.
You can define numbers like this:
$ awk '
BEGIN{
var1=2
var2=3
var3=var1+var2
print var3
}'
Or perform string concatenation like this:
$ awk '
BEGIN{
str1="Welcome "
str2=" To shell scripting"
str3=str1 str2
print str3
}'
As you can see, AWK is a powerful scripting language.