In Android there are three common modes of share internet connection with other devices: via USB cable, via Bluetooth and via a Wi-Fi access point, but without a doubt the latter is the most common.
By creating a Wi-Fi access point with your mobile you allow other devices to use the Internet thanks to the data connection of your mobile, so it is important that you have under control the use of data that these other devices do. Otherwise, the process is really easy and in most cases involves simply pressing a button.
First, configure your access point
Android mobiles come with an access point ready to be used, although you will hardly know its name and password. So you must first configure it, but only the first time: the rest of the times the last configuration will be kept.
The quickest way to get to the hotspot settings is by pulling down the Android notification shutter and doing a long touch on hotspot. Note that other Android manufacturers may use slightly different text. Once inside the section, tap on WiFi access point.
The two most important sections to configure are the access point name and password. Tap on each of these sections to set them freely (or check the value set, if you don’t remember the password).
If you want to go one step further, there is two advanced options that you can configure, although they are totally optional. On the one hand, by touching security you can choose between WPA2 PSK or None, in which case the connection will not have a password (note: older versions of Android may include other options such as WEP or WPA). Also, tapping on Access point band you can choose between the 2.4 or 5.0 GHz band.
When you finish, go back to save changes. Generally, you will not have to return to this screen the next times you want to share your connection, as long as you (or the device that is connecting) remember the password.
Then activate the access point
With the access point configured, the only thing missing is the easiest thing: activate it. You can do it from the same configuration screen, although the fastest way without a doubt is using its quick setting: tap on WIFI zone and it will turn on after a few seconds, automatically disconnecting the Wi-Fi connection if it is activated.
You can then search the connection with your other device and log in using the password you set in advance. When a device connects to your access point, it is indicated to you in a notification.