I see there are a few members here who enjoy collectingdefinitives
also called regular issues as compared
to commemoratives or special issues.
These were and are the workhorses for carrying the mail.
Even though a lot of the sets have the same design throughout
the whole series, usually heads of states, the different
colours make a page of them really stand out.
I will start of with the Denmark's wavy line definitives.
One of the longest running same design definitive series
ever and new values are still being issued.
The design was first used in 1905, printing via typography
Below is Scott 61 issued in 1912
They were redrawn in 1933, hearts have been removed, numerals are in
double line oval but now they are line engraved.
Scott 223 1933
Below are the mint ones I have, hopefully someone here can add more.
Here is link to a site which shows all the examples.http://www.frimindeks.dk/Denmark/wavy%20line.html