A computer is a computational device which is used to process the data under the control of a computer program. Program is a sequence of instructions along with data. While executing the program, raw data is processed into a desired output format. These computer programs are written in a programming language which are high level languages. High level languages are nearly human languages which are more complex than the computer understandable language which are called machine language, or low level language.
Between high-level language and machine language there are assembly language also called symbolic machine code. Assembly language are particularly computer architecture specific. Assembler is used to convert assembly code into executable machine code. High Level Programming Language are portable but require Interpretation or compiling to convert it into a machine language which is computer understood.