Highlights from Fermi Gamma-Ray Space Telescope observations of Gamma-Ray Bursts

The Fermi Gamma-Ray Space Telescope has more than doubled the number of Gamma-Ray Bursts (GRBs) detected at high energies ($>100\;$MeV) within its first year of operation. Thanks to the very wide energy range covered by Fermi's Gamma-ray Burst Monitor (GBM; $8\;$keV to $40\;$MeV) and Large Area Telescope (LAT; $25\;$MeV to $>300\;$GeV) it has measured the prompt GRB emission spectrum over an unprecedentedly large energy range (from $\sim 8\;$keV to $\sim 30\;$GeV). I will present highlights from Fermi GRB observations focusing mainly on the prompt emission phase. Interesting new observations will be discussed along with some of their possible implications, including: (i) What can we learn from the Fermi-LAT GRB detection rate, (ii) A limit on the variation of the speed of light with photon energy (for the first time beyond the Planck scale for a linear energy dependence from direct time of arrival measurements), (iii) Lower-limits on the bulk Lorentz factor of the GRB outflow (of $\sim 1000$ for the brightest Fermi LAT GRBs), (iv) The detection (or in other cases, lack thereof) of a distinct spectral component at high (and sometimes also at low) energies, and possible implications for the prompt GRB emission mechanism, (v) The later onset (and longer duration) of the high-energy emission ($>100\;$MeV) compared to the low-energy ($< 1\;$MeV) emission that is seen in most Fermi-LAT GRBs.