A database management system (DBMS) is computer software designed for the purpose of managing databases. DBMSes may use any of a variety of data models, such as the network model or relational model. The role of a DBMS in a larger system is to allow other software, or users, to store and retrieve data in a structured way.
A "Database management system is a software that defines a database , stores the data, supports a query language, produces reports, and create data entry screens.
Below is an excellent website, going over several topics in DBMS terminology. 
Finding the Best DBMS for Your Needs Edit
Most businesses make extensive use of Microsoft Excel and Microsoft Access to manage data. These are powerful and effective tools that sharing data that these tools were not designed to address.
Excel and Access are designed for single user access to entire documents. The minute a second employee tries to access the same document, a message “Open for Read-Only?” pops up. The purpose of this message is to ensure data integrity is maintained. A business doesn’t have to grow much before these messages escalate from a mere annoyance to a full-blown crisis. This is what a DBMS, which is more sophisticated, is designed to solve. It controls access at the record level - such as a single row within a document. This lower level of access is technically complex to achieve but ultimately provides huge benefits.
A second issue is that data is often replicated many times in many spreadsheets. Over time these spreadsheets evolve into multiple versions of the truth because they are not all updated as the underlying data changes. For example, when a customer moves, the address change may not be applied to all the affected spreadsheets. Similarly, when a last-minute adjustment to revenue is unevenly applied, it leads to different revenue and net income graphs being produced for the same time period. A DBMS reduces these misleading discrepancies significantly.
What are the other Primary Functions of a DBMS? Edit
It manages concurrent access to data in a predictable, repeatable and controlled manner for multiple end-users. For example, banking systems and airline reservation systems use a DBMS to provide global access to data. • Also, it is an important component of making data available on every device across the business. For example, a DBMS and its supporting computing infrastructure enable quick access to purchase orders or to customer purchase histories. • A DBMS can make the same data available to multiple applications, and enables the sharing of customer data across order entry, invoicing and accounts receivable. • A DBMS creates backup data copies for disaster recovery. Data can be quickly recovered and operations restored after a fire or a data management error.
The Key Factors Edit
The Operating System
Microsoft SQL Server 2005: Windows XP, Windows 2000+
MySQL 5: Windows (even down to 98?), Linux, Unix, Mac
PostgreSQL 8.3: Windows 2000+, Linux, Unix, Mac
So depending on the system, these choices must reflect the way your system is currently designed.
When it comes to installation and maintenance, look at the system. How much time do you want to spend with your DMBS? Some can become very time-consuming and involve major resources in your computer. Microsoft vs. MySQL is an example of this. Microsoft SQL server can take a lot more resources than MySQL. But that also can make it more powerful.
How advanced are you with a DBMS? Such options like looking at views. Or views inside of views. Depending on the level of the user, system, or the schema, features can be very useful.
Security within the DBMS protects the integrity of the data, records, and the databases. Providing encryption protection at the data level and allowing organizations to have another layer at which to manage and control all access. Major elements of DBMS security include user authentication, user authorization, encryption of data, passwords, and the auditing user actions. Take into account security built at the firewall, app, and in the DB.
This can become a big issue in finding the proper DBMS. Oracle is more enterprise level. It can handle enormous database sizes. With this edge, Oracle becomes much more expensive than the Microsoft SQL version. Depending on the level of the developer and the complexities of the system, the user can pick their more viable choice.
When looking at conversion, negotiate with the DBMS vendor for a better ratio that closely reflects your existing database workload. Deciding which database licensing model to convert to will depend on the type of application that runs against the DBMS.
Installation of Drivers
When having a DBMS installed the "finding the correct driver", issue can come into play. The application, driver manager, driver, data access software can be configured differently on each machine, from small business to enterprise. Issues ranging from a MySQL to an Oracle server, based on drivers available in the system could occur. The following shows different aspects of system/client/server ratios
Types of DatabasesEdit
Database management systems are able to support many different types of databases. The way databases are classified are according to the number of users, the database location, and the expected type and extent of use.
Single-user database: Supports only one user at a time. If user A is using the database user B or C must wait until user A is through.
Desktop database: A single-user database that runs on a personal computer.
Multiuser database: Supports multiple users at a time. When a multiuser database supports a relatively small numbers (smaller than 50)
Workgroup database: Supports a small number of users (usually fewer than 50) or a specific department within an organization.
Enterprise database: Used by an entire organization (usually 100's of users) across many departments.
Centralized database: Supports data located at a single site.
Distributed database - Supports data distributed across several different sites.
Operational database: A database designed to support the company’s day-to-day operations. Also referred to as transactional or production database.
Data Warehouses: focuses on storing data used to generate information required to make tactical or strategic decisions.
Popular Database Software PackagesEdit
-Developed by Microsoft, one of the most popular database software packages. This database software is one of the easier to work with and available with the Microsoft Office suite.
-Forms can be created within Access as well as through an ODBC connection to a more powerful database.
-While relatively easy to use and setup, Access has some disadvantages. One primary problem is that it doesn’t support SQL commands that database administrators may be used to.
-Similar to MS Access, FileMaker Pro is another powerful desktop database solution.
-FileMaker Pro supports ODBC to connect to a more powerful server solution without having to know SQL commands
-Another product developed by Microsoft, is a step up from Microsoft Access. MS SQL is a stable “out of the box” type of software package.
-MS SQL runs on its own server, supports SQL type commands, and has native support for ASP.NET and PHP.
-While much more functional than Access, MS SQL also carries a large price tag that may put smaller business off.
-My SQL is a great open source database package with a large following. Being open source is great for small budgets, but lacks any sort of product support. However, being as popular as it is, administrators may find searching the internet to be sufficient support.
-As the name implies, MySQL has SQL type commands and has support for PHP and ASP.NET