Moblogging is adding writing or photos to a blog from a mobile phone — or, in the early 2000s, from a small handheld computer called a PDA. The word had a moment when phones first got cameras and the internet, and people were excited to post from the street instead of sitting at a desk. You hardly hear it now. People just say they posted from their phone, or they talk about social media, not “moblogging.” It is informal and already a little old-fashioned; treat it as a history-of-the-web word more than as something you need for daily English.