Asymmetric warfare is that between opposing forces, which differ greatly in military power. It typically involves the use of unconventional weapons and tactics. For example, this could look like the use or cars, bombs and/or knife attacks in public places.
Furthermore, terrorist tactics such as hijakings and suicide bombings are considered to be asymmetrical, as they involve smaller groups of individuals attacking civilians whom are undefended.
As such, when terrorist groups lack the ability to take power militarily or politically, they may launch terrorist attacks to attract media coverage.