safari will not connect to internet on data (works on wifi)

Thanks for your prompt, thoughtful, and succinct response. I did have the primary "mobile data" setting on, but after scrolling down within the data setting I found all my apps listed with individual switches. And guess what -- the Safari app was inexplicably off (which is of course why it was the only one of my comms apps being data-inactive). Switching that on solved the problem. Thank you for nudging me to revisit the setting; I had no idea each app could be controlled independently for data. I hope this correspondence helps others with a similar conundrum.