Hi @Evicii,
I suggest you to watch the lecture about the GW public data (youtube link) and to read the text of the tutorial 1.1 (link), both addressing your doubts.
I list here a summary of the replies:
- GW stands for Gravitational Wave. In the name of the events, after GW you see the date of the event with 2 digits for the year (yy), 2 for the month (mm) and 2 for the day (dd), e.g. GWyymmdd. For example GW150914 is the event recorded the 14th September 2015. In the most recent events you find also the hours of the event so the nomenclature is something like GWyymmdd_hhmmss where hh denotes the hour, mm denotes the minute and ss denotes the second of the event;
- LVT was used only once for an event detected the 12th October 2015, i.e. LVT151012. At the time of the first analysis the event not significant enough to claim an unambiguous detection, and it was published but with a different name. However, after an improved re-analysis of the data, the significance increased and now it is officially listed as GW151012. The acronym LVT stands for Ligo Virgo Transient.
- H1 and L1 are short names of the two LIGO detectors (see also this reply to another question)
- O1 means first Observing run; all the periods of observation are indicated with “O” followed by a number and eventually a letter if the run was divided in two parts, for example O3a and O3b denote the first and the second part of the third observing run
- S5, S6 are the periods of data taking before the detectors had enough sensitivity to hope to see a GW events. In this case S stands for Science run.