About Computer

A Computer is a machine which helps us to calculate, simulate and store different scenarios. For example, in order to write an e-mail, instead of paper and pen first we use a software (or program) called wordprocessor which helps us enter sentences through keyboard (Input), computer's screen (output) to read, and modem (output/input) to send it to a distant relative, friend, etc.
The mechanism to simulate a regular mail into an e-mail, gave us a very fast and much cheaper medium to communicate (not a simulation anymore). Same way, using computers we can simulate other things over which we do not have any control, for example weather, behaviour of atomic bomb, behaviour of a deadly virus, Earthquake, a innovative design for a new auto, airplane, machine, etc.
Any computer has five parts Input, Output, CPU, Memory, disk (storage) . Input is things like mouse, keyboard, modem. Output is computer screen, printer. CPU or central processing is brain of the computer which controls and execute all calculations, manipulations and output. Memory (RAM)is a temporary storage to be used by CPU when doing calculations, etc. Think of it as a scratch pad for CPU. Disk is permanent storage, on which all the software and data is stored.

Database

A database is a software which lets user to organize their data in an orderly fashion. For example consider a company which sells cookies, they have a database of which has tables (or records) of customers, types of cookies and orders. So when customer x orders n number of x type of cookies his orders is placed in table orders. There are several type of databases. Some which are simply text files with records, others which are complex with tables of information. A table of information means "an array of one type of records", for example "an array of customer names, addresses, phone numbers". A Relational database is in which there are relations among the tables, for example consider three tables with customer info, inventory info and orders info. The relations between these three tables define the relational database. So when a customer X from customer table orders Item Y from Inventory info it is put in Orders table, there are links in these tables (through primary keys, secondary and foreign keys such Social Security number, product number, order number, etc) which lets us do that and thus making it a relational database. Popular type of relational databases are Access for PCs on windows 95, Oracle, Sybase, Informix, for huge business environment (running Unix operating systems).