These bands are good for local communications.
They are considered line of sight. Line of sight means that for every 1ft off of the ground, the signal has the potential to go one mile. So a 6ft person with an HT held next to their head can theoretically talk 6 miles.
This is not exact because the person you are talking to might be 10ft tall. Giving y’all a combined distance of 16 miles. Also radio waves will follow the curvature of the earth a little ways.
With line of sight could talk to the International Space Station (ISS).
Just remember that trees, leaves and structures can block or reflect the signal as well.
There are certain frequencies within these bands that limit your wattage. FRS, MURS, and GMRS limit the power you can use on certain frequencies. However, more power will help you get more distance so I recommend getting an Amateur Radio Operators license.
Find a Repeater that you are allowed to use with the frequencies you are licensed to use, and have fun reaching out 20, 30, 40 miles
If you want to step up to real long distance, even using low power, you need to get a “General” license. You can easily talk around the world although you can’t call a direct area, it is still fun to talk to some one in Hawaii
- Hope this was a good quick overview