Final answer:
The statement that buying at a CPM rate means that you're only buying impressions by the thousand and not individually is true. CPM, or 'cost per mille', implies that advertisers pay for every thousand impressions of their ad.
Step-by-step explanation:
Programmatic advertising is a field within online advertising that involves the automated buying and selling of ad inventory in real-time through software. The statement that buying at a CPM rate means that you are only buying impressions by the thousand and not individually is true. CPM stands for 'cost per mille', where 'mille' means thousand in Latin. Therefore, when advertisers buy ad impressions on a CPM basis, they are paying for the opportunity to present their advertisement to 1,000 viewers or site visitors. It's a common pricing model for programmatic ads, as well as other forms of digital advertising.