Yes. Decoding a base64 encoded string will give you back the exact original data.
Importantly though, this isn’t what you’re seeing when you open files in a text editor as you describe in your original post, and if you copied the text of those files and saved a new copy it’s very likely that it would not reproduce correctly.
But its still contains the actual data in a faithfully reproducible/useable way?
Yes. Decoding a base64 encoded string will give you back the exact original data.
Importantly though, this isn’t what you’re seeing when you open files in a text editor as you describe in your original post, and if you copied the text of those files and saved a new copy it’s very likely that it would not reproduce correctly.
yes, this method doesn’t lose any bits. one of its primary use before was email which was strictly text only.