What do "Cc:" and "Bcc:" mean?

Cc: stands for "carbon copy." Anyone listed in the Cc: field of a message receives a copy of that message when you send it. All other recipients of that message can see that the person you designated as a Cc: recipient received a copy of the message.

Bcc: stands for "blind carbon copy." This is similar to the Cc: feature, except that Bcc: recipients are invisible to all the other recipients of the message (including other Bcc: recipients). For example, if you send a message To: johndoe@yahoo.com and Bcc: janedoe@yahoo.com, then johndoe sees himself as the message's only recipient. Janedoe, on the other hand, is "in the know"—she can see that you sent the message To: johndoe, and that you blind-copied her. To add an entry in the Bcc: field, click the "Show BCC" link to the right of the "To:" field.

What are seeds and leechers (peers) in torrents?

Number of seeds and leechers (peers) play an important role in determining the download speed of torrent file. So what exactly is meaning of torrents (bittorrent, utorrent) seeds and leechers?

What are seeds?
A seed is a client that has a complete copy of the data of a certain torrent. Once your BitTorrent client finishes downloading, it will remain open until you click the Finish button (or otherwise close it). This is known as being a seed or seeding.

What are leechers?
A leecher is a client that is currently downloading the data of a torrent. A leecher does not have the complete file, otherwise it would be called a seed.
Conclusion:
Seeds have the complete file and are actively sharing ... peers are downloading the file and have part of it and usually are sharing pieces also ... high numbers of each are best for speed ... low numbers of seeds and high peers will make it slow .. low numbers on each will make it slow ......