The Semantic Model tab describes the shape of your data — which tables you're using, how they join, what columns exist. Business Context is where you say what any of it means.
A column called Salesamount is a fact about your database. "Monthly Sales" is a fact about your business. Business Context is where the second one lives, so that everyone building workbooks reaches for the same definitions instead of inventing their own.
It has three parts.
Measures — the numbers
A measure is something you count or add up: revenue, orders, average deal size. Each one carries a formula, and it can carry a plain-English description so a reader knows what it's for.
There are three kinds:
Standard — an aggregation of a single field, like the sum of a sales column
Calculated — built from other measures or an expression
Conditional — behaves differently depending on a condition
Dimensions — the ways you slice them
A dimension is what you break a number down by: product, region, month, customer.
Three kinds here too:
Field dimension — straight from a column in your model
Drill-through — a path from a summary down to underlying detail
Bucket — groups values into ranges or bands, like age groups or price brackets
Lineage — where a number comes from
Lineage draws your model as a chain, reading left to right: the tables you're using, the fields inside them, and the measures built on top.
It answers the question people actually ask about a number on a dashboard — where does this come from? Follow the line back from a measure and you'll see exactly which fields and tables it rests on.
The toolbar has a search box for finding something in a large model, a colour key for the kinds of node — tables, fields, dimensions and measures — and zoom controls.
Tip: you don't have to come here to use it. Any measure's ⋮ menu has Show in lineage, which opens the graph with that measure already in view.
Next: Choose Define a measure in Business Context, Create a dimension, or Get suggestions from your data if you'd rather Astrato propose some to start from.