There is a load of reasons you might want to stop hearing from someone, whether it's telemarketers, annoying promotional text messages, your weird uncle, or a friend from high school who is convinced you should reconnect and become best friends.
Fortunately, it's really easy to stop them from contacting you on an iPhone if you know where to look.
There are two paths you can follow to block someone. The first is simple but only works if the person you want to block is already in your contact list. Go to "Settings" and then click on "Phone." In that menu, there's an option called "Call Blocking & Identification." It's simply labeled "Blocked" on older versions of the iOS. Once there, click "Block Contact" and then select who you'd like blocked from your contact list.