Hard drive (or ssd) encription

Dear Logan, Wendall, Quain, or pistol

 

I am Probally just paraniod but if I wanted to encrip my hdd/ssd (so nobody can just steal it and take what ever ever they want off it) what is the best way I.E. fastest, easiest, hardest to crack. I am wondering this because I have some very important documents on both my hdd and ssd and I dont want people to beable to take my computer (its right next to a sliding glass door) and get anything off it. Another question of I need someone to get stuff off my hdd like my family how does a key work, is it a password or a something else I'm not quite sure.

 

- Robert