Informality is often associated with blogs because of their informal nature. This means that there is less emphasis on grammar and spelling, and more on content.
This can make a blog feel more like a conversation between friends than a formal document.
However, there are some formal elements to a blog. For example, all posts must have a title, and each post must have at least one sentence.
Additionally, posts must be well-organized and complete. In other words, they should present an orderly argument and not just a series of thoughts.
Overall, blogs are largely informal, but there are some formal elements that must be followed in order to maintain the format.