EC2 instance types: DRMCGIFTPX

D2 = Dense storage — file servers, data warehousing and hadoop ***
R4 = (RAM) Memory Optimized — memory intensive applications and databases ***
M4 = (Main) General purpose — applications servers
C4 = Compute optimized — CPU intensive applications and databases ***
G2 = Graphic intensive — video encoding, #d application streaming ***
I2 = (IOPS) High speed storage — NoSQL databases, data warehousing, etc. ***
F1 = Field Programmable Gate Array — hardware acceleration for your code
T2 = (T2 micro) lowest cost, general purpose — web servers and small databases
P2 = (Python) graphics, general purpose GPU, machine learning, bit coin mining
X1 = (eXtremme RAM) Memory Optimized — SAP HANA, apache spark
thanks to acloudguru