I find many people are a put off from having a Microsoft or Google account because it is often confused with holding an account with a local company, in other words, at some point one expects to get an invoice. This is not accurate and in fact in the case of Microsoft, Google, Yahoo, Apple etc it is entirely possible to have an account and pay nothing. Apple will ask you to provide a form of payment but it will never be used providing you don’t purchase anything from their app store.
In a nutshell an account is simply that you have access to email, storage and, if included, office applications and the free levels of service offered are usually fine for most people.
A Microsoft account will give you free access to email, 5Gb of storage on Onedrive (Microsoft’s cloud storage) and access to their on line office applications.
A Google account will give you access to email, 15Gb of free storage and their on line office. It should also be noted that if you have an Android phone or tablet, and if you use the Google Photos app you can have free unlimited photo storage – Google just reduces the quality of your pictures a little (They still look great) but if you want your pictures to stay exactly as they are then you may choose not to do this and start paying for extra storage after reaching the 15Gb allocation.
You can also use the Google Photos app on Apple devices (it’s also known as Google Sync – especially on desktops) and have the same free unlimited storage. See my post here about this.
An Apple account (icloud.com) is usually attached to an apple product but also gives access to an online world. You can log in via icloud.com and use online versions of Apple’s office software and also send/ receive email.
Also worth reading – Why you need to link your mobile with your email provider