There is still a widespread believe that Apple Macs do not get viruses, Trojans, spyware and other types of malware, but this simply is not true. It is much safer to access the internet with a Mac running OS X than a Windows PC, but it is not completely safe and some types of malware target Apple users. After installing OS X Yosemite you should open Safari and fix the security and privacy issues that afflict it.
A brand new Mac works brilliantly and it is a joy to use. It is fast, responsive and works a like a dream. Later on though, it might become more like a nightmare. The fact is that computers slow down over time and the older they are, the slower they become. There are several ways to restore lost performance and one popular one is to use a disk clean-up tool like 
Go to the Mac App Store, go to Categories, select Utilities and the number two app in the free chart is Memory Clean. It is second only to OS X Yosemite. It is a very popular app, but do you really need a memory cleaner? What does it do?
Do you know the answer to these questions off the top of your head: How many days are there until the end of the month? Your next holiday? Your birthday or anniversary? Even if you are good with dates, these questions are hard to answer. Would you like to know? The 
Preview has had the ability to capture your signature and insert it into documents for some time. You could sign your name on paper, then hold it up to the camera and it would scan it in. Now in the OS X Yosemite version of Preview, you can sign your name on the trackpad. It is an interesting alternative and one that is worth experimenting with. Let's see how to add a signature.