unsolicited
Not asked for or requested by anyone.
Unsolicited means not asked for or not requested. When something is unsolicited, nobody invited it or said they wanted it.
If you walk up to a classmate and start giving them advice about their art project without them asking for help, that's unsolicited advice. Maybe they appreciate it, or maybe they'd rather figure it out themselves. The point is they didn't request your input.
Companies often send unsolicited mail trying to sell you things you never expressed interest in buying. Your email inbox probably fills up with unsolicited messages from businesses you've never contacted. These are also called spam.
While unsolicited things can sometimes be welcome (like an unsolicited compliment about your presentation), the word often carries a slightly negative tone. It suggests something that might be intrusive or unwanted. When someone says “thanks, but I didn't ask for your opinion,” they're essentially saying your opinion was unsolicited.