user4325: Whenever I send bitcoins from one wallet or one exchange to the next there is always a fee. This makes sense with the exchange sites, they are just collecting the fee so they can make a living. What about the open source wallets that I've installed on my computer? 
Surely, nobody is collecting my bitcoins because my transactions are too long! So, is the "fee" part of the Bitcoin algorithm? Do the coins that are confiscated in the fee go to Bitcoin miners?
Also, when does the fee start? I noticed, if I send like 0.05 bitcoins there is no fee, but if I send 0.1 bitcoins there is a fee. 
What if I just sent 0.05 bit coins twice? Or is it if they are in the same block I will get a fee, so I'd have to send them twice (and 10 minutes apart)?

user153: From the Bitcoin.it wiki:

Transaction fees are voluntary on the part of the person making the
  bitcoin transaction, as the person attempting to make a transaction
  can include any fee or none at all in the transaction. On the other
  hand, nobody mining new bitcoins necessarily needs to accept the
  transactions and include them in the new block being created. The
  transaction fee is therefore an incentive on the part of the bitcoin
  user to make sure that a particular transaction will get included into
  the next block which is generated.


http://en.bitcoin.it/wiki/Transaction_fees

The client might send one transaction for free but then for the next transaction (even if it is for a smaller amount) the client might show that a fee is required.  This is likely due to the makeup of the remaining coins in the wallet.  After your first transaction, any change that was made gets sent back to you but that becomes a "newly received" coin.
To the network, if that second transaction includes this newly received coin that would look the same as a transaction made by someone trying to harm the network.  That type of harmful action tries to re-spend the same funds over and over but without paying a fee.
So just like how there might be a candy dish on a receptionists desk and you are free to take one doesn't mean you are free to take all the candy from the dish.
That's the same approach here.  The client will let you spend coins that have some time passed (i.e., were not just received) without having to pay a fee.
If your coins are instead being re-spent within a short amount of time (i.e,. same day), then the presumption is that you could be harming the network therefore a fee is required to prevent that activity.  If it was a transaction being made without the intent to harm the network, then requiring a small fee shouldn't be that much of a restriction.

user85: The fee goes to the miner who mines the block that includes your transaction. The fee is based on the size (in bytes) of the transaction and the age of its inputs (how long ago the coins spent were received).
Transactions get big if they have to "pull in" a lot of outputs from previous transactions and that raises the fee. So if you got a lot of small payments and then try to make a large payment, the transaction will be expensive because it needs to gather all those small payments.

4325: <p>Whenever I send bitcoins from one wallet or one exchange to the next there is always a fee. This makes sense with the exchange sites, they are just collecting the fee so they can make a living. What about the open source wallets that I've installed on my computer? 
Surely, nobody is collecting my bitcoins because my transactions are too long! So, is the "fee" part of the Bitcoin algorithm? Do the coins that are confiscated in the fee go to Bitcoin miners?</p>

<p>Also, when does the fee start? I noticed, if I send like 0.05 bitcoins there is no fee, but if I send 0.1 bitcoins there is a fee. 
What if I just sent 0.05 bit coins twice? Or is it if they are in the same block I will get a fee, so I'd have to send them twice (and 10 minutes apart)?</p>
 153: <p>From the Bitcoin.it wiki:</p>

<blockquote>
  <p>Transaction fees are voluntary on the part of the person making the
  bitcoin transaction, as the person attempting to make a transaction
  can include any fee or none at all in the transaction. On the other
  hand, nobody mining new bitcoins necessarily needs to accept the
  transactions and include them in the new block being created. The
  transaction fee is therefore an incentive on the part of the bitcoin
  user to make sure that a particular transaction will get included into
  the next block which is generated.</p>
</blockquote>

<ul>
<li><a href="http://en.bitcoin.it/wiki/Transaction_fees">http://en.bitcoin.it/wiki/Transaction_fees</a></li>
</ul>

<p>The client might send one transaction for free but then for the next transaction (even if it is for a smaller amount) the client might show that a fee is required.  This is likely due to the makeup of the remaining coins in the wallet.  After your first transaction, any change that was made gets sent back to you but that becomes a "newly received" coin.</p>

<p>To the network, if that second transaction includes this newly received coin that would look the same as a transaction made by someone trying to harm the network.  That type of harmful action tries to re-spend the same funds over and over but without paying a fee.</p>

<p>So just like how there might be a candy dish on a receptionists desk and you are free to take one doesn't mean you are free to take all the candy from the dish.</p>

<p>That's the same approach here.  The client will let you spend coins that have some time passed (i.e., were not just received) without having to pay a fee.</p>

<p>If your coins are instead being re-spent within a short amount of time (i.e,. same day), then the presumption is that you could be harming the network therefore a fee is required to prevent that activity.  If it was a transaction being made without the intent to harm the network, then requiring a small fee shouldn't be that much of a restriction.</p>
 85: <p>The fee goes to the miner who mines the block that includes your transaction. The fee is based on the size (in bytes) of the transaction and the age of its inputs (how long ago the coins spent were received).</p>

<p>Transactions get big if they have to "pull in" a lot of outputs from previous transactions and that raises the fee. So if you got a lot of small payments and then try to make a large payment, the transaction will be expensive because it needs to gather all those small payments.</p>
