PuTTY is a free open source SSH/Telnet terminal emulation program for Windows and Unix like operating systems. PuTTY terminal emulation is xterm compatible and configurable. PuTTY can also be used to tunnel X11 over a secure link.
There are a suite of programs available for use with PuTTY:
PuttyGen: A tool for generating public key encryption pairs for use with PuTTY and OpenSSH.
Pageant: the PuTTY Authentication Agent used for storing Keys and providing them when requested to PuTTY utilities.
PSFTP: An SFTP clinet.
PCSP: A command line scp clinet.
PLINK: A command line connection utility similar to ssh that can be used for automating connections and tasks.