I know I use lots of terms when blogging, so this page is here to help you understand anything I write and don't yet understand.
HF - High Frequencies, from 3mhz to 30 mhz
VHF - Very High Frequencies, 30mhz to 300 mhz
UHF - Ultra High Frequencies 300mhz - 3ghz
QTH - Radio operators home location
RFI - Radio Frequency Interference
QRM - Man made noise or interference on the radio frequencies
(DMR) Digital Mobile Radio - open digital radio standard for professional
mobile radio & amateur radio users
Repeater - A radio system that operates on two frequencies, and re-transmits your signal with more power. Allowing mobile handhelds to have greater coverage.
Digital Repeater - Same as above but also connected to the internet. Uses the internet as propagation connecting 1000's of radios all over the world via Talk Groups.
FT8 - A digital mode that can work with very low signals to make semi automated QSO's. This is not conversations but a basic swap of signal reports between stations.
WSPR - Small low powered radio transmitter used to send your callsign to check propagation of your signal. Other stations around the world who hear your signal submit live reports via the internet to the WSPR website where you can see where you are being heard on a global map.
Raspberry Pi (rpi) - Small one board computer which runs linux. Used in many projects I build.