• Posting Key (Recommended, can be used to upvote/comment/post)
• Active Key (All permissions of posting key + Ability to transfer funds)
  read more about it here
  https://steemit.com/steem/@shenanigator/updated-steemit-faq-section-security

your long password that you receive when you first activate your account is very important to keep in secure vault since if it's lost it can not be recovered. I use LastPass it has mobile app to store all my passwords securly. Even LastPass do not have access to the passwords, its highly recommended. You can get free month premium if you use my invitation link https://lastpass.com/f?9780236 it's $12 a year. You can use it for free after that. I believe mobile is free. Not bad. Also read about 2nd factor authentication. This adds extra mechanism of authentication to make it a little more difficult if someone tries to access your account.