There could be many reasons why a visitor lands on a page and then leaves all of a sudden. Some if the main reasons could be:

If the visitor lands on a page where the content didn’t meet their needs or expectations, then they will most likely leave the website, causing the analytics software to register a bounce. When searching for something in particular in Google or other search engines, people have certain ideas of what they can expect when clicking on a result, however, sometimes the content doesn’t meet those requirements or doesn’t answer the questions they have, and so they look somewhere else.

If a page has an unattractive design or a difficult or confusing user experience, then it makes it difficult for the user to interact with that content or website and get value. Great design & UX encourages visitors to engage with the content, stay on the page, and explore the website easily.

Sometimes, a bounce can occur because the page or content fulfilled the needs of the visitor in a short period. For example, if they had a specific question and the page they landed on answered the question briefly near the top of the page, then it served its purpose, even though the visit was registered as a bounce. This can be avoided by structuring the page or copy so that it compels the visitor to scroll down the page and start engaging with the content before they find what they are looking for.