Thank you is an expression of gratitude against one's favour. When people receive a help during their needy situation saying a thank you is a custom as it is a token of appreciation. Thank you can be said on many occassions like when a wish is received it is a courtesy to thank the person who wishes. Sometimes a person's being in our life brings a lot of difference in good ways and helps in a betterment of our life,that person always deserves a hearty thanks. It is a feeling of appreciation. The state of being grateful,warm and friendly feeling toward a benefactor,kindness awakened by a favor received,thankfulness.