Why do some European languages using the Latin alphabet have fewer or more than 26 letters?

European languages using the Latin alphabet have varying numbers of letters due to historical adaptations and the need to represent unique sounds. The Classical Latin alphabet originally had 23 letters, with some being dropped or added over time.12

For instance, the letters J and V were differentiated from I and U respectively during medieval times, contributing to the 26-letter alphabet common in English. Some languages omit letters like K and W, while others incorporate additional letters. These additions often take the form of standard Latin letters modified with diacritical marks (like accents or umlauts) or combinations of letters to represent sounds not present in the original Latin. This process of adapting the Latin alphabet to different languages allows for the accurate representation of their specific phonetic systems.12