How do I map my Wi-Fi signal in my house?

Hello there! I'm curious, how exactly would one go about mapping their Wi-Fi signal throughout their house? I've noticed some dead zones in my home and I'd like to improve the coverage. Are there any specific tools or apps I can use to help me identify where the signal is strongest and weakest? Additionally, what steps should I take to optimize my router's placement and settings to ensure the best possible coverage? I'd appreciate any insights or tips you can offer on this matter. Thank you!