The activity timeline is the panel on a Lightning record page that lists every task, event, logged call and email for that record in date order, with what is still to do at the top. Think of it as a paper planner clipped to the customer file: the open page shows what is due, and the pages behind it show what already happened.
If you support a sales or service team, this is where reps look before every call. When it is missing or shows the wrong things, they stop logging work. We built a small set of activities in a Winter ’27 org for this post, so the screens below are real.
By the end you will know how the activity timeline in Salesforce is organized, why a record’s timeline can show activities from other records, how to put it on a page, and where its data lives in SOQL.