The importance of keeping your users passwords and sensitive data is important, when storing data there are several calls in php which will encode the data to a point that it is difficult to realize what it is.
A quick example can be found here:
There are two types of data encryption.
Two Way Encryption
Two way encryption is used when someone will need to reuse the data, for instance, if you have a document that is important for the two parties, it will encrypt the data to send it, and when the other person receives it, they will be able to use the data once it is unencrypted.
One Way Encryption
One way encryption is used for passwords, and just about any other user input, but mostly passwords, this makes it so the letters you type will be encrypted and when you type them again, the program will send those letters in various ways to match, but it cannot be rematched.
When collecting payments or using sensitive data it is important to have a SSL certificate, this enables encrypted data through a server, a article about this can be found here with many options,
Different Methods of Encryption
There are so many different ways to create data security, if you are interested, try searches like, salt and pepper password protection. This adds custom letters at certain points and help to create a more secure database so if you ever get hacked, they will not know how to unencrypt the data and share it with thousands of black market websites.
It is always good to know that your data is safe, with custom website development you can know that your data is protected and kept safe just in case someone hacks your data.