I seem to have different definitions when it comes to names than most people, so before I really get started here, I want to explain my reasoning and rationale behind some of the terms I use.
One, I firmly believe that there is a difference between "popular" and "trendy". I believe that something can be popular, but classic, therefore, making it not fall under the "trendy" label. These would be names like Emma, Ava, Isabella.....they are all very popular, but still classics. A "trendy" popular name is something like Madison. It's a surname, which is a trend, but it's also popular.
THEN, to make this even more confusing, you can have a trendy name that's NOT popular. Randomly adding -Lyn to a prefix (take Ry, for example) is a trend and just because "Rylyn" is not "popular", does not mean it's not "trendy".
Second, I often group classics and vintages into one category. I might label thing like Catherine and Ruby in the same category, even though they technically are not.
Lastly, is my "international" or "exotic" beauties. These are one's that are not often heard within the US, but have roots in a different country or culture.