To Play your land for the turn or not?

Playing a land for the turn is something that many people do automatically without thinking too much about it. However sometimes you have no use for the mana that turn so keeping the land in hand conceales information from your opponent. He now has to consider the unknown quantity. Now, keeping the land can punish you. Lets say you have 2 lands in hand and 4 in play. By keeping the lands in hand you cant play a topdecked 6drop next turn.

Sometimes people play their land when they shouldnt, for example if someone is in tpdeckmode with 9 land in play. They draw their 10th land and immediatly plays it even if they have no use for it. It can be correct to do that but only in specific circumstances. Otherwise its betetr to hold it to keep information from your opponent.

There is a rule  (that has some exceptions) that you can always keep 1 land in hand to bluff. The reason is that if you need the land you can just play it next turn. If you draw a land next turn you just play out one of them and you are in the same position as the turn before.

However as with all rules it has exceptions. I remember a long time ago i was playing an Avacyn restored draft and i kept 1 land in hand to bluff, the only card in my hand. My opponent then played Into the Void his next turn (It bounces 2 creatures) For my next turn  i topdecked a land and since i didnt play my land last turn I couldnt play both my creatures and i lost.

Reasons to keep a land:

To bluff

To be able to discard them to certain card (Tormenteffects, cards with activated abilities that require discard, Brainstorm

Reasons to not keep a land:

Bouncespells

Opponent may discard your land and suddenly you topdeck a card you need the mana for.

You may topdeck a carddrawspell (Hieroglyphic illumination) and draw into a a land and a spell you need all your lands for.

This is a tricky subject, but at the very least, just dont play your land every turn automatically.