What does it mean that there is a vertical line in the middle of each text in the WeChat chat record?

Text messages are separated by vertical lines, and each message has a unique label to distinguish different messages. The sent picture will have a picture label and the expression will also have an expression label. The function of these tags is to help find messages. If you want to find an email, these tags are used to locate it. The chat records of WeChat are stored in the mobile phone. If you don't change your mobile phone and clean up your chat history, then the data will always be saved.