What does the "X" mean in magic the gathering?

Question

sitting here holding the blaze sorcery cad in my hand.

Answer 1

X on the upper right corner of the card means that you can pay any amount of mana. In the case of blaze, it will deal X damage to target creature or player. If you pay 5 it will deal 5, if you pay 6, it will deal 6, etc.

If the X is black and its located between the text box and the art, then it is the expansion symbol (meaning that it belong to tenth edition).

Answer 2

it means u can pay whatever amount of mana u choose, even zero.  U can pay it with any color mana.  So 4 example if I blaze u and pay 5 for X then u take 5 damage.

Answer 3

When you see X in the manacost and an X in the effect text, it means it depends on how much mana you paid. Any other X's depend on what the card says it depend on. Hope this helped!