No G questions but Cloud questions. I dont use the cloud. For anything. Don't understand it. Worry about hacks.
I completely appreciate concerns about "hacks", but you cannot control how other entities (individuals, banks, insurance companies or government agencies for example) protect your personal information. The only thing you can control is how much of your personal information you choose to reveal to them. You really don't have much of a choice when it comes to some of those entities, but you do with most others.
The most egregious and damaging "hacks" have been breaches of the very entities you are required to use. For example, the United States Office of Personnel Management was one of the largest breaches of government information in history. It revealed personal information sufficient to effectively commit identity theft on a grand scale – affecting millions of people not limited to those employed directly or even indirectly by the US government or contractors.
By far the worst custodians of personal information have been government agencies, banks, and insurance companies – various entities that we are often required to use by law.
Since you mentioned Yahoo, it too suffered a similar fate they deliberately covered up for a long time, with damage claims likely to drag out in court for years. Yahoo does not store fingerprints and security clearance background checks like the OPM did, but they lost control of hundreds of millions of accounts.
There are countless other examples of egregious security breaches with more of them appearing seemingly with each passing day.
As bad as that record of trust is concerned, by far the largest threat faced by everyone is the willful divulging of personal information through various "phishing" exploits, which routinely employ constantly shape-shifting forms of deception. Learn about that by reading Avoid phishing emails, fake 'virus' alerts, phony support calls, and other scams - Apple Support.
Rhetorical question: You don't understand iCloud, yet you understand Gmail? Google's business model relies upon the harvesting of personal information so that they can sell it to others, whereas Apple takes an almost polar opposite approach. In fact Apple has made repeated and highly publicized statements regarding the degree to which they respect and protect their customers' privacy, even to the point that it puts them at a competitive disadvantage in various services that provide personalized information tailored for your exclusive use.
Contrast that with Google, which doesn't even try to hide the fact it routinely collects and sell your personal information by whatever means necessary. To worry about iCloud but not about Google just doesn't make sense.
So can you explain like I'm 10 how it works?
Read about iCloud and its many services here: iCloud: What is iCloud? Apple's enormous investment in iCloud services is fundamental to its success.
How secure is iCloud? Good question. If Apple were to suffer a breach of account security similar to the few examples I mentioned, about a billion people would be affected all over the world. The gravity of such a horrific prospect is not lost on them. For one reason, Apple is by far the largest single holder of credit card account information on the planet. Losing even a tiny percentage of that information would be financially disastrous, with devastating worldwide economic effects.
The weak link in iCloud security is you. As far as that is concerned, Apple aggressively promotes the use of two-factor authentication for your Apple ID, which is effective and (as such things go) unobtrusive enough to actually use.
In terms of breaches and "hacks" reveal only what you are required to reveal in order to use the services you require. If someone or something asks you for information, even if your answer is "yes", simply refuse to answer. Find out who's asking, and why.
