iTunes is a media player and media library application developed by Apple Inc. It is used to play, download, and organize digital audio and video on personal computers running the OS X operating system and the iOS-based iPod, iPhone, and iPad devices, with editions also released for Microsoft
iCloud is a cloud storage and cloud computing service from Apple Inc. The service allows users to store data such as music and iOS applications on remote computer servers for download to multiple devices such as iOS-based devices running iOS 5 or later, and personal computers running OS X 10.7.2 "Lion" or later, or Microsoft Windows (Windows Vista service pack 2 or later).
iCloud is Apple's cloud-storage subscription service. iCloud Drive is like an external hard disk in the sky. Available for iOS devices, Macs, and Windows PCs. Let's you access all of your files and data from any device
Steps to Sync Contacts from iPhone 4s/5/5s/6/6s to Mac via iCloud:
1. On your iPhone, tap Settings > iCloud > Sign in with your Apple ID > Find Contacts option here and toggle it to ON.
2. On your Mac, if you haven't enabled your iCloud on Mac, you should set it up first. Go to System Preferences > Find and open iCloud > Sign in with your Apple ID > Select Contacts to enable it. After that, all your iPhone contacts are synced to your Mac via iCloud.
Note: OSX Mavericks v.10.9 or later, your contacts, calendars, and other info are updated on your computers and iOS devices via iCloud.
When installing a third party application such as iTunes ensure that the following recommendations are fulfilled:
1. You have administrative rights to the computer
2. Get latest Windows updates
3. Disable any conflicting software; you can use MSCONFIG utility to troubleshoot the problem in Vista or Windows 7.
4. Make sure your folder names don't contain strange characters
5. Additionally, if you are installing unsigned software, you will be prompted whether you are willing to go ahead with the installation. You must accept to the risks to complete the installation.
Example: The problem is that Jason was not able to update contacts and getting an error "Unable to Connect to the Server". The problem may be solved by:
1. Checking the health of the iCloud server. If the iCloud server is down, usually, it will be fixed by the company in a few minutes.
2. Verifying his login credentials. Sometimes, if you are not able to connect to the iCloud, it might be due to verification failure. Just login to iCloud from both your iPhone and the desktop and verify login credentials. In most cases, this will solve the problem. You may need to restart your devices before doing this and close any other applications before verifying your credentials.