A proper noun is the name of a person, place or thing (i.e., its own name). Proper nouns are always written using capital letters.
David, Blackpool Tower, Westham United, Antarctica, Ceylon, Watership Down, Dayton Peace Accord, Wigan Pier, Monday, April, Jupiter
Remember, a proper noun is written with a capital letter, because it is a name or a title. Do not give a word a capital letter just because it is an important word in your sentence.
As a valued Client, you have been selected for a special Gift.
Glossary of grammatical terms