Also searched as: sale and purchase agreement
The clauses that matter most sit in the annexes: the anticipated completion date plus the developer’s grace period (often 6-12 months), the area tolerance (a percentage by which the delivered size may vary without compensation), and what happens to your instalments if you default. Read those three before signing anything.
This explains the general case. If SPA has come up in a live deal of yours, talk to the team: specific answers, registered numbers, no obligation.