Understand Creative and Ad flow

To a newbie in an advertisement technology company, acquiring business knowledge is a major obstacle.
Recently I came across a concept which I found interesting but not quite obvious: Creative. After seeking explanations from a veteran in the company (Mr. Tran Duc Toan), it turned out that the concept should be understood within a broader context. Recognizing the importance of this knowledge, I choose to post the context explained by Mr. Toan, for the benefit of our future newbie. The context is expressed by a drawing which typifies an Ad flow like below.

The Ad flow begin from the left-top corner of the drawing:

• a Client (who pay to post an advertisement which suits his/her needs) request an Ad Agent to post an Ad.
• Upon accepting the request, the Ad Agent (in the middle lane) will create materials for the advertisement, which can be in various media format, such as image or video, accompanied by simple “catch phrase” in text. These Ad material are sometime called Raw data. This is step numbered 1 in the flow.
• Next, in step numbered 2, the Ad Agent will submit these Ad materials to target Ad platforms (such as facebook, etc.).
• The submitted Ad materials will be validated, inspected and judged by the platform whether or not they are accepted and approved by the platform. In case the materials are approved, they will be stored in the platform (accessible via facebook Album for example) with specific identities created and assigned to them by the platform. These identities are then returned to the Ad Agent in the form of Image Hash or Video ID at step 3. At this step, the submitted and approved Ad materials become Creatives. A Creative can be further edited by the Ad Agent, and finally take a form of a single Image, a Carousel, or a Video.
• After receiving the needed identities of the Creatives, the Ad Agent may go on to create Ad entities (step 4) or transfer the identities to the Client and the Client create Ad entities themselves. An Ad entity then will be displayed on a Web browser, attracting Web surfer’s attention.

This is the general context of Advertisement business as I understand. Within that context, to me, a Creative is an Ad material which already stored in an Ad platform with a specific identity, ready to be used to form an Ad.

Still I am fully aware that this understanding may be not accurate yet. If you notice any inaccuracy in the content above, please point out for me. Thank you very much.

—I would like to accredit this post to Mr. Toan, for his generous explanation and helps—