How to track cellular data usage and roaming on iPhone?

so to track seller data usage just open settings go to Cellular and then here in the bottom you will have cellular data you can track two options seller or data current period meaning the the whole period of um like all cellular data usage and then there is a separate tab which says current period roaming which means if you're traveling in another country and you have your Roman enabled so you have several data options you can just enable that and then you will just see that also apply to roaming but yeah there you have it that's how you can track if you have some kind of a cap on the usage for example in EU like if you're there is no additional charge for some data usage in roaming but there is a smaller data set it can be like 10 gigabytes or something like that 12 gigabytes so it's important to track that