A mobile hotspot, in layman’s terms, is a portable device that allows a number of other devices (such as laptops, smartphones, tablets) to connect wirelessly to the internet, which it does by sharing the 3G or 4G LTE signals from your cellular provider. If you have cell service, you can have bandwidth to share.
So why get a mobile hotspot? Naturally, they’re not for all. A smartphone is enough for most means of connectivity, or, if your data plan allows for “tethering” — connecting your smartphone directly to another device to take advantage of its cellular signal — you can use your phone as a mobile hotspot. However, there are drawbacks to this, such as your phone’s battery will deplete quickly and you, most likely, won’t be able to make calls or receive calls. (The hotspot will interrupt the cellular connection.)
But, if your laptop needs internet access (or multiple people or devices do) and it needs to stay connected in the fastest way possible, a mobile hotspot is an easy and reliable way of acquiring data. As for which mobile hotspot to buy, that depends on the type of traveler you are and the cell service you use.
Here's some options to consider: