The quest log

The quest log lists exactly what you must do next.

What it shows

The main quest of your current act: its steps in order, with a title, a short text and the current objective.
Your active sub-quests, each with its own steps.
Completed quests, so you can check what you have done.
A hint for each step, for example where to go or who to talk to.

Objectives. Steps are one of four kinds: talk to someone, kill a number of creatures in a place, reach a place, or defeat a boss. Hand-ins are done by greeting the NPC again.

Never stuck. Every step has a hint, and every act ends by naming the next hub. If you lose track, the log's top entry always says where to go.

Death and logout. Quest items such as shards are never lost. Your place in the story is saved with your character.

Skipping (coming soon). In later seasons a character from an account that cleared the campaign starts as Seasoned: it can skip the tutorial and the dialogue (Seasons).

Not in the log. The Atlas and the faction progressions are tracked in the atlas windows (The Atlas, Standing and Tokens).