I'm reading this pki article and as you can see near the bottom, the quick animation and description:
The sending computer encrypts the document with a symmetric key, then encrypts the symmetric key with the public key of the receiving computer. The receiving computer uses its private key to decode the symmetric key. It then uses the symmetric key to decode the document.
So my question:
1: This description seem to describe asymmetric encryption model, but then why are they encrypting it with a symmetric key?
2: Why bother using a key at all to encrypt the document? Why not just encrypt the document with the public key directly and decrypt it with the private key on the receiving computer?