PuTTY opens a text terminal to another computer, network appliance, or serial device. The remote machine runs the shell and commands; PuTTY displays their output and sends the user’s keyboard input back across the connection. This differs from Windows Terminal or Command Prompt when they run a shell on the local computer. PuTTY can connect through SSH, Telnet, rlogin, SUPDUP, or a serial port, and its companion commands handle scripted sessions and file transfer.
Remote sessions
A new connection begins with a host name or address and a protocol choice. SSH normally carries an encrypted terminal session, while a serial session talks to a local COM port and needs the correct speed and line settings. It does not create an account on the remote machine. The server still decides which username, password, key, shell, and commands the session can use.
The command line can start an SSH connection with putty -ssh host.name. This is useful for shortcuts, but many configuration choices remain easier to store in a named session. Its companion program Plink exposes terminal connections to scripts, while PSCP and PSFTP transfer files. Those programs can refer to a saved session name instead of repeating its connection settings.
Saved connections
It does not save every connection automatically. The user enters a name in the Saved Sessions box and presses Save. A later launch can select that name in the window or use putty.exe -load “mysession”. The saved record holds connection and terminal preferences, but it does not turn a server password into a reusable login secret.
Windows stores these session records under the current user’s registry profile. Moving the executable to another computer therefore does not carry the saved sessions with it. A portable workflow needs an explicit registry export or a fresh configuration on the other machine. This split often surprises users who expect all settings to sit beside the executable.
Host keys
On the first SSH connection to a host, it has no cached host key to compare. The confirmation dialog shows the key fingerprint so the user can verify it through a trusted channel before accepting it. Acceptance records that host key for later connections. If the server presents another key afterward, it warns instead of silently replacing the cached identity.
A changed key can follow a legitimate server rebuild, but it can also indicate that the connection reached another machine. Pressing through the warning without checking removes the protection that the comparison supplies. The cache identifies the server; it does not prove that a downloaded private key belongs to the intended user.
Clipboard input
It follows terminal conventions that differ from ordinary Windows text fields. Its default paste action uses the right mouse button or Shift-Insert. A right-click can therefore send clipboard text straight to the remote shell rather than opening a context menu. Pasting several lines may execute commands immediately as the remote shell receives newline characters, so command text needs inspection before that click.
Local traces
It keeps saved sessions and cached SSH host keys in the current user’s registry. Windows can also list recently used launchable sessions in the PuTTY jump list. A saved session marked as non-launchable avoids that jump-list entry while remaining available inside the main window. The -cleanup option removes its registry data and jump-list information for the current user. It is a destructive cleanup step, so it also removes useful saved sessions and trusted host-key records rather than erasing only a recent-history list.
