The Through Train is an advertising platform under Alibaba. Merchants can use the Through Train to place advertisements to increase product exposure and sales.

The general principle of the Through Train is as follows:

1. Merchants create a promotion plan on the Through Train platform and select the products and target audiences that need to be advertised.

2. Merchants set advertising budgets and bids, decide which keywords and positions to display ads, as well as parameters such as the display time and frequency of ads.

3. The Through Train system displays ads on e-commerce platforms such as Taobao and Tmall according to the advertising parameters set by the merchant, attracting users to click into the merchant's store or product details page.

4. When a user clicks on an ad, the merchant needs to pay a certain advertising fee for this click. The Through Train system deducts this fee and returns the remaining fee to the merchant.

5. Merchants can use the data and reports provided by the Express system to monitor the advertising effect and ROI in real time, optimize advertising strategies and budgets, and improve advertising effects and revenue.

It should be noted that the advertising effect and revenue of the Express system are affected by many factors, including the quality of advertising creativity, keyword selection, bidding strategy, competitor situation, etc. Merchants need to formulate reasonable advertising strategies and budgets based on their actual situation and needs, and continuously optimize and adjust advertising effects to achieve better advertising effects and revenue.