Do expats pay taxes in Spain?

Could you please clarify for me the tax obligations of expatriates residing in Spain? I'm curious to know if expatriates are required to pay taxes in Spain, and if so, what kind of taxes they might be subject to. Would it depend on their nationality, the duration of their stay, or other factors? Also, how does Spain handle double taxation, if an expatriate is already paying taxes in their home country? Could you provide some insight into this matter? Thank you for your assistance.