offer and invitation to treat

what are the 2 questions that you need to ask in order to see if an offer has been made?

where is the definition of offer found ? what does it say?

a proposal amounts to an offer if..

what can you look at to determine whether there has been an offer or an invitation to treat ?
case?

what are Ads, brochures and price lists ?
case ?

what are shop displays ?
cases?

what does DCFR say?

what are websites ?
so when is the offer then made?

what about auctions ?

what do shop keepers have the right to do?

so, what about in terms of self service ?- when is the offer made?

cases ?