1. Gratefulness

2. How to say gratefulness
"Thank you" is the most common way of expressing gratitude. I am grateful for you I am thankful that I have you in my life (someone might say this about their spouse, for example). I am grateful to you I am thankful about something you did to help me; I feel indebted to you for your kindness.

3. Saying thank you to a store clerk
Here are some things you can say:
"Thanks for your help."
"Thanks a lot, this has been very helpful."
"Thank you so much."
"Thanks."
"I appreciate your help. Thanks a lot."
"Great, thank you."

4. Saying thank you to a colleague
Here is what you can say: "Wow, that's so nice of you." "What a nice surprise." "I didn't expect that, thanks a lot." "You read my mind, thanks.“ (You are implying that he figured out that you were craving coffee) "Thanks a million.“ (used more when you write a thank you note) "Much appreciated“ (used when you write a thank you note)

5. Saying thank you to your boss
Here is what you can say:
"Thank you for your time today.“
(By or in person)
"I really appreciate your taking the time to meet with me today."
"Our meeting was very helpful. Thanks so much."

6. Saying thank you to a close friend
Here's how to say thank you:
"You have been a lifesaver, thank you.“
(This means that you were really in need of help and she was there at the right time)
"I'm really thankful for your generosity."
"Thank you for everything you've done for us."
"I don't know how to thank you."
"I can't thank you enough."