What are symptoms that someone has an addicted to something? is it that they crave it and get excited right before they do it?

Depends on what kind: of addiction. For many substances (like alcohol. sedatives and opioids) there are MANY other symptoms, because the individual has become physically dependent on the drug. So alcoholics have tremor, anxiety, sweating, elevated pulse and blood pressure, opioid addicts have diffuse pain, diarrhea, vomiting and other symptoms. Craving and relief-seeking is common to all of them.

Tolerance+Withdrawal: The hallmarks of physical addiction = (1) physical "dependence" - user experiences withrawal symptoms if stops using/taking it (happens w/many substances, incl meds 4 high blood pressure); & (2) "tolerance" -over time, user requires higher & higher amounts of the substance 2 get same effect. User experiences cravings in relation to cues that become associated w/substance -time of day, place, etc.