Life is transitory. No permanent reality inside or outside the person, except the source of all things seen and unseen. Each person is made up of parts that are changing. Tanha is thirst or craving. No matter how much we acquire, we cannot be permanently satisfied.
Desire is insatiable and it results in discontent and misery.
Most people delude themselves into thinking that possessions, attachments, relationships represent the essence of happiness, but these are just the cause of dukkha . Concentrate on the present moment, not on the past or future, or one's desires. Release from suffering is possible by following the Eightfold Path. The ultimate goal in Buddhism. It is not total annihilation, though.