Do I need a router to use my phone as a hotspot?

Laurie wants to know if she needs a router to use her phone as a hotspot. Leo says no, the phone acts as a router. Her speeds will depend on how many devices she's using with that hotspot, and how many other people are using that tower. Laurie uses it because it's cheaper than paying for internet access at home. Leo also says that mobile phone operating systems are also more secure than desktops.