Afik HanahalCaveat (Hearat Azhara)
In short
After you sign the contract and before the property is in your name, a caveat in the Tabu is the "sign" telling everyone: this property is already sold. Without it, the seller could in theory sell again or mortgage it.
The professional explanation
The caveat is registered under section 126 of the Land Law on the basis of a written undertaking (the contract). Once registered, no conflicting transaction is registered without the beneficiary's consent, and the caveat also protects against later attachments and the seller's bankruptcy.
It is registered immediately after signing, usually by the buyer's lawyer, for a fee. The mortgage bank registers a caveat in its favour as well.
An existing caveat in favour of a third party is a warning sign for a new buyer: there is a prior deal, mortgage or undertaking to investigate and remove.
Example from the field
A Tabu extract for a Hod Hasharon plot showed a caveat in favour of a buyer from a deal cancelled years earlier but never removed. The sale was delayed until the seller located the previous buyer and obtained consent to remove it.