What is the maximum hand size in magic the gathering?

Answer 1

"217.3b. Each player has a maximum hand size, which is normally seven cards. A player may have any number of cards in his or her hand, but as part of his or her cleanup step, the player must discard excess cards down to the maximum hand size."

"Maximum Hand Size: Each player's maximum hand size is normally seven cards, though effects may modify this. As the first part of the active player's cleanup step, if he or she has too many cards in his or her hand, that player chooses and discards as many cards as needed to reduce his or her hand to its maximum size (but no more than that). See rule 314, "Cleanup Step." "

So the maxumum hand size is 7 unless an effect of an card has changed it.