Virtual Hosting

Virtual hosting is a method for hosting multiple domain names on a computer using a single IP address. This allows one machine to share its resources, such as memory and processor cycles, to use its resources more efficiently.
One widely used application is shared web hosting. Shared web hosting prices are lower than a dedicated web server because many customers can be hosted on a single server.


Types
Name-based
Name-based virtual hosts use multiple host names for the same webserver IP address.

With web browsers that support HTTP/1.1 (as nearly all now do), upon connecting to a webserver, the browsers send the address that the user typed into their browser's address bar (the URL). The server can use this information to determine which web site, as well as page, to show the user. The browser specifies the address by setting the Host HTTP header with the host specified by the user. The Host header is required in all HTTP/1.1 requests.

IP-based
In IP-based virtual hosting each site (either a DNS hostname or a group of DNS hostnames that act the same) points to a unique IP address. The web server is configured with multiple physical network interfaces, virtual network interfaces on the same physical interface or multiple IP addresses on one interface.

The web server can obtain the address the TCP connection was intended for using a standard API and use this to determine which website to serve. The client is not involved in this process and therefore (unlike with name based virtual hosting) there are no compatibility issues.

Port-based
The default port number for HTTP is 80. However, most webservers can be configured to operate on almost any port number, provided the port number is not in use by any other program on the server.

Forex trading

The investor's goal in Forex trading is to profit from foreign currency movements. Forex trading or currency trading is always done in currency pairs. For example, the exchange rate of EUR/USD on Aug 26th, 2003 was 1.0857. This number is also referred to as a "Forex rate" or just "rate" for short. If the investor had bought 1000 euros on that date, he would have paid 1085.70 U.S. dollars. One year later, the Forex rate was 1.2083, which means that the value of the euro (the numerator of the EUR/USD ratio) increased in relation to the U.S. dollar. The investor could now sell the 1000 euros in order to receive 1208.30 dollars. Therefore, the investor would have USD 122.60 more than what he had started one year earlier. However, to know if the investor made a good investment, one needs to compare this investment option to alternative investments. At the very minimum, the return on investment (ROI) should be compared to the return on a "risk-free" investment. One example of a risk-free investment is long-term U.S. government bonds since there is practically no chance for a default, i.e. the U.S. government going bankrupt or being unable or unwilling to pay its debt obligation.

When trading currencies, trade only when you expect the currency you are buying to increase in value relative to the currency you are selling. If the currency you are buying does increase in value, you must sell back the other currency in order to lock in a profit. An open trade (also called an open position) is a trade in which a trader has bought or sold a particular currency pair and has not yet sold or bought back the equivalent amount to close the position.

However, it is estimated that anywhere from 70%-90% of the FX market is speculative. In other words, the person or institution that bought or sold the currency has no plan to actually take delivery of the currency in the end; rather, they were solely speculating on the movement of that particular currency.