Thought is what happens in your mind when you think: an idea, opinion, or mental picture that forms inside your head. When you have a thought about what to do this weekend, your brain is creating possibilities and considering options. When a thought crosses your mind during math class, it might be about the problem you're solving or about something completely different, like what you'll do at recess.

Thoughts can be simple, like “I'm hungry,” or complex, like working through how to build a treehouse or figuring out why your friend seemed upset. Some thoughts arrive suddenly, like when you remember something you forgot. Others develop slowly as you puzzle through a problem or imagine a story.

The word also refers to careful consideration or mental attention. When you give thought to a decision, you're taking time to think it through properly. Teachers might ask for your thoughts on a book, meaning they want to know what ideas formed in your mind while reading it. Scientists have thoughts about how the universe works; these thoughts become theories that they test with experiments.

Your thoughts are private until you share them through words or actions. You can keep a thought to yourself or express it out loud. Unlike feelings, which you often experience in your body, thoughts happen in your mind as you process information, solve problems, or wonder about the world.