A linker or link editor is a computer program that takes one or more object files generated by a compiler and combines them into a single executable file, library file, or another 'object' file.

It is also called link editor and binder, a linker is a program that combines object modules to form an executable program.

Computers are classified in to three types based on their principles of operation. These three types of computers are

Analog computers
Digital computers
Hybrid computers
Analog computers

Analog computer is a computer that performs operations using continuously varying signals such as voltage, current and frequency. In analog computers numbers are represented by continuously varying quantities such as voltage, current and frequency. 

Analog computers are mainly used for scientific and engineering purposes. These computers do not give completely accurate results. The accuracy of analog computers is less. Analog computers do not require memory for performing operations.

Antikythera mechanism is the first known analog computer that is designed to predict astronomical positions and eclipses. This instrument was designed and constructed by Greek scientists between 150 and 100BC.

Digital computers

Digital computer is a computer that performs calculations and logical operations using electrical signal such as voltage that is represented in two digits 0 and 1. Where 0 and 1 represents two different voltages or states, 0 represents 0V or OFF state and 1 represents 5V or ON state. 0 or 1 is called bit.

Most of the computers available today are the digital computers. The computers that we use at home or offices are digital computers.

Hybrid computers

Hybrid computer is a computer that has features of both analog and digital computers. These computers use analog part for performing the mathematical calculations such as differential equations and digital part for performing the logical operations and for storing result. Hybrid computers have the speed of analog computer and accuracy of digital computer.

A relational database management system is a database management system that is based on the relational model invented by Edgar F. Codd, of IBM's San Jose Research Laboratory.

All modern database management systems like SQL, MS SQL Server, IBM DB2, ORACLE, My-SQL and Microsoft Access are based on RDBMS.

Data is represented in terms of tuples (rows) in RDBMS.

Relational database is most commonly used database. It contains number of tables and each table has its own primary key.

Due to a collection of organized set of tables, data can be accessed easily in RDBMS.

The difference between an interpreter and a compiler is given below:

Interpreter       /     Compiler

1)Translates program one statement at a time.     /   Scans the entire program and translates it as a whole into machine code.

2)It takes less amount of time to analyze the source code but the overall execution time is slower.    /    It takes large amount of time to analyze the source code but the overall execution time is comparatively faster.

3)No intermediate object code is generated, hence are memory efficient.   / Generates intermediate object code which further requires linking, hence requires more memory.

4)Continues translating the program until the first error is met, in which case it stops. Hence debugging is easy  ./     It generates the error message only after scanning the whole program. Hence debugging is comparatively hard.

5) Programming language like Python, Ruby use interpreters.   /     Programming language like C, C++ use compilers.