Am I taxed on sale price - purchase price? Or appraisal price

[James Robert]

I purchased a home for 183k back in Jan this year. It is now worth about 240 with my updates I did. 

Lets say it sells for 240.. Am i taxed on the 57k (240-183=57) or I am taxed the difference between the 240 and the appraised value when i bought it? It appraised for 215 at the time.  So that would be only a 25k difference.

Please let me know!! Itching to find out. 

Thanks!