過去ログとはなんですか？
A chat log is an archive of transcripts from online chat and instant messaging conversations. Many chat or IM applications allow for the client-side archiving of online chat conversations, while a subset of chat or IM clients (i.e., Google Talk and Yahoo! Messenger 11 Beta) allow for the saving of chat archives on a server for future retrieval. Most [IRC] clients and many [IRC bot]s include chat logging to a local file as a standard feature.
A chat log is an archive of transcripts from online chat and instant messaging conversations