This document is currently being written, but in brief.....
Putty is a popular terminal emulator. It is an open-source, light-weight, and free SSH client, developed by Simon Tatham. Putty can store the address of multiple SSH servers, providing 'speed-dial' access to them. One it's many useful tricks is to allow the background colour of the session to be set, which is useful if you have a small number of servers and want to colour code their sessions for easy identification. Obviously you have to choose the colours carefully to ensure you don't have a background colour that makes coloured text hard to read, for example where an ls command shows various files, folders, symlinks and so on in different colours, but black (#000000), charcoal (#202020), dark blue (#000020), dark red (#200000) and dark green (#002000) all seem to work pretty well as background colours.
Putty is free to download from PuttyGen.