Peek allows you to look into or 'peek' into the fields in another table
eg. Peek('Sales', 0) gives you the first record in the 'Sales' field
Match gives you the position in an expression of the value passed to it
eg.Match (M, 'Jan', 'Feb')
where M=Feb returns 2
applymap is the equivalent of 'vlookup' in excel (although has some excellent advantages). So, by using a mapping load, you can switch out on field (say an ID field) for another (say a description)
