Overall, the word nostalgic (adj.) means looking back on the past with fondness. Sometimes nostalgia is sad or bittersweet, but this is mostly a happy emotion.

Can nostalgia be happy?

Because nostalgia is both an emotion and a thought process, it's considered a blended emotion and different than other emotions. For instance, when you're happy, you can simply be happy, but when you're nostalgic it involves the cognitive process of remembering, which also has emotions attached to it.

Is nostalgia sad or happy?

Higher levels of nostalgia are also related to a search for meaning in life. This study suggests that people who rate themselves as more nostalgic tend to have more negative feelings and emotions than those who rate themselves as less nostalgic.