The first step in a home purchase transaction, Pre-Qualification is a casual conversation with your Loan Officer which establishes your ideal price range.
Now that you know your price range, you can refine your search for your next home.
Accepted Offer and Contract
You found a house in your price range and geographic area, made an offer (including but not limited to any negotiations of the sale price, repair requests, and closing/move-in date), and it was accepted. Once accepted, this back-and-forth results in the Contract, sometimes known as a Purchase & Sale Agreement.
Now that you have your Contract in hand, you can officially apply for your home loan. Your Loan Officer will be reaching out for additional documentation (tax documents, pay stubs, bank statements, etc), so pay attention to that request. The faster these documents are received, the faster your loan can move through the process.