A smartphone is a portable device that combines mobile telephone and computing functions into one unit. It is a cellular telephone with an integrated computer and other features not originally associated with telephones such as an operating system, web browsing, multimedia functionality, the ability to run software applications, along with core phone functions such as voice calls and text messaging. The existing brands for Smartphones nowadays are: Samsung, Xiaomi, iPhone, Nokia, Huawei, Google Pixel, HTC, Asus, LG, Alcatel, Infinix, Panasonic, BlackBerry, Tecno, TCL, Oppo, Realme, Gionee, ZTE, Sony, Vivo, Lava, Lenovo, Microsoft, and Motorola. Choosing a smartphone for yourself not easy task. Factors that affect your choices of Smart phone are: price range, features, the operating system you prefer, the important specs for you. To help you to pick the best smartphone for you, I provide here briefer review for the specifications of different types of smartphones along with some helpful customer reviews in order to see ow the customers evaluate the product. This report consists of the following sections: 1. Price comparison of different budget smartphone models. 2. The differences between 2G, 3G, 4G LTE, 5G networks and WIFI. 3. The differences between NFC and Bluetooth. 4. The differences Android and iOS. 5. How to choose a smartphone by brand, carrier, or features. 6. How to keep your phone from overheating. 7. Security issues according to Check Point. 8. Samsung. 9. Xiaomi Redmi. 10. Xiaomi Poco. 11. Apple. 12. Nokia. 13. Huawei. 14. Google Pixel. 15. Microsoft. 16. Realme. 17. Sony. 18. Others mobile brands: HTC, Asus, LG, Alcatel, Infinix, Panasonic, BlackBerry, Tecno, TCL, Gionee, ZTE, Oppo, Vivo, Lava, Lenovo, Motorola, Meizu, Honor, OnePlus. 19. References.