Bitcoin wallet address keeps Changing

Bitcoin - The only cryptocurrency with mass adoption
Cryptocurrencies have existed in various forms for nearly 50 years now, all of them either crashed or failed for some reasons. Bitcoin is the only digital currency with wide adoption, deep structure, and trading momentum. No other cryptocurrency ever gained such a huge popularity and adoption worldwide. World's leading websites such as Facebook, PayPal, Ebay, Yahoo, Wordpress etc. are accepting Bitcoin for shopping.
Not just online shopping, some colleges, hospitals, clinics and shopping malls have also started accepting Bitcoin, for example in Finland dentists accept payment in Bitcoin, pint can be purchased through Bitcoin in Berlin, and even you can buy a vacation house through Bitcoin in Argentina. Moreover, giant multinational companies such as Western Union, AT&T, Fidelity, etc. are also accepting Bitcoin and the number of retailers and online ecommerce platforms, that accept payments in Bitcoin, are rising every day.
How Bitcoin beat the US Dollar and Precious Metals?
The value of a Bitcoin jumped by 9, 100% during the year 2013, yes we are talking about mere 12 months from Dec. 2012 to Dec. 2013. On the other hand, the US Dollar, which is believed to be the most reliable currency on earth, has been losing its value constantly for about a century now. Federal Reserve's unprecedented monthly stimulus package, worth billions of dollars, and other unpopular policies accelerated the depreciation in the US dollar during recent past. In fact, the Dollar has lost about 96% of its value since 1913, the year when Fed came into being. The Dollar has depreciated around 50% since 1985, against a basket of major currencies, and 33% of that depreciation was realized in last 11 years.
Same is the case with precious metals. Gold, which is considered to be a "safe heaven" in economic recession, last year, witnessed the biggest annual slump since 1981 as investors lost faith in the yellow metal. Gold nosedived around 28% during 2013...

Even with increased popularity and acceptability, Bitcoin is still very uncommon in many parts of the world especially in developing countries, where internet and technology is not very common.