I owe my deepest gratitude to a lot of people, including my family and my friends.

This book is for my dad, Abdelkebir; I know how proud you are of me but I want you to know how proud I am of you; you've always been an engine for me, I love you. My mom, Halima; thank you for your unconditional love and support, I love you, and this book is for you. My sisters Soundous, Kaoutar, and Souad for always supporting and telling me that they are proud of me, I love you.

I would also like to thank all my friends, especially Mounir, who does not miss a chance to encourage me and to tell me that I can achieve this and who bought me candies so I'd have sufficient energy while I was writing this book, thank you brother, you are the best. Also a big thank you to Youssef for his daily encouragement and for giving me all the support I needed, you are my big bro. I also want to thank Simohamed Ghannam, Ayoub Faouzi, Kamal, Abdelouahed, and all the others whom I have not have listed here.

I want to tell all of you that I feel proud of this achievement because of your help, support, and love. Thank you all.