After buyer and seller have signed the Purchase Contract and any counter offers, the real estate agent typically “opens escrow” by forwarding escrow a copy of the fully executed Purchase Contract and the buyer’s deposit check. Escrow, is an independent neutral third party; works impartially for both Buyer and Seller, and is authorized to follow the specific written instructions provided by both parties.

Escrow Functions:
Receives and deposits (into escrow’s trust account) buyer's initial deposit and prepares escrow package.
Requests "demands" (pay-off statements) from lien holders.
Obtains Seller's notarized signature on grant deed; safeguards grant deed until all terms and conditions are met and Buyer’s remaining certified funds are on deposit.
Continually coordinates with Buyer's lender; Orders and processes Buyer's loan documents. Coordinates Buyer’s signing of loan documents and their return to Buyer’s lender. Receives Buyer's final down payment funds and coordinates funding with Buyer's lender.
Calculates prorations pertaining to property taxes, insurance, interest, and any other expenses as required. Distributes funds: pays-off existing encumbrances; pays other required costs, such as termite completion, home protection policy; brokerage commission, etc. Releases net proceeds to Seller.

Simultaneously, the Buyer and their lender are working towards the loan approval. Lender Functions:
Orders a credit report and other credit documentation as required (mortgage ratings, landlord ratings). Reviews the Buyer's credit and if applicable obtains satisfactory explanations from the Buyer regarding any negative credit.
Verifies the Buyer's sources of income.
Verifies that the Buyer has adequate liquid funds for down payment, closing costs, and reserves.
Requests an appraisal of the property, and verifies that the property's value is sufficient collateral.
Submits the loan for final approval.
Coordinates delivery of the Buyer's loan documents to the escrow officer. Reviews the executed loan documents received from escrow, schedules funding (cutting the check) and coordinates recording (transfer of title) with escrow.

And in the meantime... While the escrow officer, lender, and Buyer are diligently working, the Seller and the Listing Agent also have responsibilities: 
Prepares numerous disclosures required by law to be provided to buyer.  
Provides escrow officer information on existing liens.
Has the home available for physical inspector and other trades people as required by the purchase contract, such as licensed Termite Company and lender's appraiser.
Makes any negotiated repairs, or repairs as required by local ordinance (water heater strapping, smoke detectors, etc.).

In order for your escrow to proceed smoothly, the Realtor’s job is to coordinate and oversee the above chain of events.   Similar to dominoes – each event must occur in a timely fashion.  You need an experienced Realtor because delays in any of these events may result in the postponement of escrow’s anticipated closing date.