An instant messaging client application is executed on a first terminal, to participate in threads of instant messaging between user terminals over a packet-based network, each thread comprising exchanging text-based messages between the user terminals of a selected group of contacts comprising the first user and at least one second user. A digital record of the messages is maintained in a data storage medium. A further text-based message is received from one of the second terminals over the packet-based network, comprising a citation of a cited one of the text-based messages previously transmitted over the packet-based communication network and stored in the storage medium. The further message is processed at the first terminal so as, by reference to the storage medium, to recover a context of the cited message in relation to others of the text-based messages in the respective thread.