When looking at the symptoms of a disease, how can a doctor determine whether it is bacterial or viral?

In other words, what is the difference between how viral infections and bacterial infections affect the body? How are the symptoms between the two types of diseases different? After a doctor learns what symptoms a patient has, what further tests or examinations would he/she run to determine whether the disease is bacterial or viral?

What is a VPN?

VPN is (Virtual Private Network) were first used by companies to enable their employees to securely access internal systems such as email remotely (e.g. from home or while on business trips). Today they are increasingly being used for personal use by individuals to protect their privacy while online in public places (e.g. when using the wi-fi connection in a cafe) or in a country where the internet is censored / blocked (e.g. China, Saudi Arabia��).