The term "deposit" in the context of conveyancing refers to the money that you pay to show your commitment to the purchase of a property. The deposit is usually paid when you exchange contracts and is typically a small percentage of the purchase price.
The purpose of the deposit is to secure the purchase of the property and to show that you are serious about completing the transaction. Once you have exchanged contracts and paid the deposit, the seller is committed to selling the property to you, and you are committed to buying the property.
The deposit is usually held by the seller's conveyancer, when it is deducted from the total purchase price the difference is your mortgage amount. If for any reason the purchase does not go ahead, the deposit may be used to cover the costs of cancelling the transaction.
In summary, the deposit is a key part of the conveyancing process, and it is important to understand what it is and what it is used for before you exchange contracts on a property purchase.