# Why are some journals with low impact factor indexed in Web of Science while others with a relatively higher impact factor are not?

I'm a researcher in mathematics. While looking for journals in my field, I found out while some journals with a low impact factor are indexed in Web of Science, another Springer journal with a higher impact factor is not.

Journal indexed in Web Of Science (lower impact factor)

Journal indexed in Web Of Science (lower impact factor)

Springer journal not indexed in Web Of Science (higher impact factor)

I couldn't find an explanation, except that the Springer journal hasn't requested to be indexed in Web of Science yet. Is there another explanation of what makes some journals get indexed by Web Of Science while other journals with relatively higher impact are not?