Editing First day of issue (section)

===Postmark===
[[File:Centenary of the Red Cross cover 1963.jpg|thumb|left|1963 Centenary of the Red Cross cover with West Wellow postmark - where [[Florence Nightingale]] was buried]]

The [[postmark]] is one of the most important features of a cover. Stamps are cancelled by a postmark, which shows they have been used and cannot be re-used to send a letter. Circular Date Stamps (CDS) are the 'bread-and-butter' postmarks used on everyday mail by Post Office counters across the UK. A CDS postmark is very straight forward and only features the town’s name and the date. There is no picture. If one wanted to use a CDS postmark from a town relevant to the stamp's issue, one would have to go to the town’s local Post Office to get it. On a cover, the postmark should touch each stamp and link them to the envelope.
Postmarks came to the foreground in the early 1960s, when collectors started to demand more interesting cancellations on their first day covers. For the Red Cross issue in 1963, a special [[Florence Nightingale]] cover was posted at her birthplace, West Wellow. The Botanical Conference issue of 1964 featured primroses on the stamps, so one clever cover dealer posted his covers at [[Primrose Valley]]. This kind of relevant postmark made a cover worth often ten times more than the same cover with a standard postmark issued by the [[Philatelic Bureau]] at Edinburgh (a place with no connection to the stamps).<ref>{{cite web|last1=Buckingham|first1=Tony|title=Glossary|url=https://buckinghamcovers.com/glossary/index.php|website=Buckingham Covers}}</ref>  In the US, the U.S. Postal Service chooses a city, or several, as 'official' first day cities. These have a special connection to the stamp issue being released, and these postmarks are the only ones that have the wording: 'First Day of Issue'.<ref>{{cite web|title=A Short Course on First Day Covers|url=https://www.afdcs.org/fdccourse.html|website=American First Day Cover Society}}</ref>