Understanding slug positioning by different sites

Question

While trying to understand how to create a better URL for ease of user and not compromising on SEO, I was looking at the structure for different sites. I have a few queries related to the below ones:

• Amazon -> /typical-product-slug/dp/{id}

• stackoverflow -> /questions/{id}/question-slug

• yardsellr -> for_sale#!/product-slug--{id}

[1] Why does amazon place the slug right after the domain name when doing it like stackoverflow's makes it more easy to understand and also provides a directory structure? Also, keeping the {id} at the end makes it more prone to cut-n-paste errors.

[2] Is the difference in amazon and stackoverflow's positioning of the {id} has something to do with the {id} being alphanumeric for amazon and only digits for stackoverflow? Maybe alphanumeric is more cryptic to users and hence amazon putting it on the right most position, from SEO perspective?

[3] For amazon, isn't using the keyword 'products' or even the high level category like 'books' or 'music' in place of 'dp' makes more SEO effective?

[4] yardsellr for it's trailing {id} doesn't use a '/' but '--' as the marker. Google says depth of URL dir structure doesn't really matter much. What is yardsellr benefiting from this structure, is it a dash just because the slug and the id both unique and same? Is there something to do with the depth? If they had placed the id before the slug, does that impact the SEO?

I know there are no straight forward answers to most of these. Looking for your experience and thoughts so that I can learn.

Thanks.

Answer 1

1. SEO. Have you tried the URLs without slug?! SO can put slugs at the end, because titles can change frequently and then the URL changes too. So its better to have permalinks to SO only with the question/ID. Same with Amazon but in the other direction, they have the bigger competition and normally titles for a product don't change that often and maybe have shorter lifetime, but can also become permalinked without slugs.

2. ID is ID. Regardless. Cryptic like YT have a bigger range with less positions than auto-increasing numbers which look better. There are a lot of pros and cons.

3. Nobody searches for 'product', 'book' or 'cd'. Only titles and authors are important.

4. Always keep slugs in front for SEO, like in 1. Depth is always important.