der Dank
thanks
A feeling or expression of gratitude for help received, a gift, or a kindness.
Als Dank für seine Mühe erhielt er einen Gutschein.
As thanks for his effort, he received a gift certificate.

thanks
Loading your saved state.
thanks
A feeling or expression of gratitude for help received, a gift, or a kindness.
Als Dank für seine Mühe erhielt er einen Gutschein.
As thanks for his effort, he received a gift certificate.

'Der Dank' (thanks/gratitude) belongs to the word family of 'danken' (to thank) and 'dankbar' (grateful). All of these words relate to the concept of gratitude.
Ich möchte dir für deine Hilfe danken.
I would like to thank you for your help.
To express the reason for gratitude, German uses the preposition 'für' (for) followed by the accusative.
Vielen Dank für die schönen Blumen!
Many thanks for the beautiful flowers!
'Dank' (thanks) is part of many fixed expressions. Common phrases are 'Vielen Dank' (many thanks), 'Herzlichen Dank' (heartfelt thanks), 'zum Dank' (as thanks), or 'Dank sagen' (to say thanks).
Zum Dank für ihre Hilfe lud er sie zum Essen ein.
As thanks for her help, he invited her out to eat.
'Gott sei Dank' (thank God) is a fixed expression of relief. If it appears at the beginning of a sentence, the conjugated verb follows directly after it (inversion).
Gott sei Dank habe ich den Zug noch erwischt!
Thank God I still caught the train!
The meaning 'Lohn' (payment) or 'Belohnung' (reward) is almost always used ironically or negatively. You can recognize it when a good deed leads to a bad result.
Ich habe stundenlang auf ihn gewartet, und der Dank dafür war, dass er gar nicht kam.
I waited for him for hours, and my reward for that was that he didn’t come at all.
unfortunately
'leider' and 'Gott sei Dank' are opposites in many situations. With 'leider', you say that something is bad, unwanted, or disappointing. With 'Gott sei Dank' (thank God), you express relief because something turned out well or something bad did not happen. So this is not about gratitude in the normal sense, but about the fixed expression. Put simply: use 'leider' for bad news, and 'Gott sei Dank' when expressing relief.

Gott sei Dank hat die Ärztin heute noch einen Termin frei.
Thank God the doctor still has an appointment available today.
Leider ist der Bus schon abgefahren.
Unfortunately, the bus has already left.