Simply put, it is what someone (organization) wants to do, such as purchasing and other matters, and the clear signing form sent to a specific person.

The offeree is naturally the one who received the offer!

An invitation to offer is like sending an expression of intention to conclude a contract to an unspecified group! For example, an advertisement is similar to an invitation to offer.

Specific example: a hotel sends out various accommodation and catering advertisements to the society, which is an invitation to offer. After you see the invitation, you just want to have a meal, so you go to the hotel to make an offer (order food, make an inquiry ...), and the hotel agrees to accept your request and price. This is a promise and this contract is established!