I've exchanged a few words with people here and it seems, to my delight, that some of you are new to crypto in general and new to Steem in particular. I think it would be useful to give advice on a few things to make your Steem experience safer and more convenient.
As you know (but probably not everyone reading this), if you want to do anything but consume content on DPorn, you'll need a Steem account. Steem is a public blockchain. A blockchain is a database, a ledger, up-to-date copies of which are held on a large number of servers on the internet. All information made up of transactions committed to it by its users is organized into blocks of a certain size that appear in the database in temporal order. There are over a hundred servers on the internet called witness servers that each maintain a copy of the whole blockchain. IMPORTANT! The contents of the database cannot be edited or deleted unless a sufficient number of the witnesses agree to throw away the entire old database and make a new one from the transactions (except those that are not chosen to be included in the new one). This has never been done for the sake of changing data stored on the chain.
When you post anything to the blockchain, you should be aware of the fact that it will be there for as long as the chain exists. When you edit or delete a post or a comment or take back or change a vote what happens is that a new entry to the database (blockchain) is made. User interfaces called front ends such as Steemit or DPorn always show the latest version of the data despite the old data remaining on the blockchain. You can take a closer look at what goes on Steem at steemworld.org. SteemWorld also offers a pretty good overview of current general information about the chain. At steemworld.org/@username, you can see everything pertaining to a certain account.
Only text is stored on the Steem blockchain. All binary data (audio, images, video) is stored elsewhere. Steemit uses Amazon Web Services and DTube has used IPFS, a decentralized peer-to-peer file storage system. I'm not sure what it uses after it was revamped, though. For this reason, binary data can be edited or removed because it's never stored on a blockchain because doing so would be very expensive. Many people who use the blogging interfaces (Steemit, SteemPeak etc.) choose not to rely on Steemit to store their images but link to image hosting services on the web.
Steem has four public/private key pairs. In practice, you only need to use the private keys because you sign every transaction with them - or more precisely the app you're using does it for you. The keys exist for you to use each of them for different types of transactions requiring different levels of security.
The private memo key exists for you to decrypt private messages sent to you encrypted using your public memo key. Memos on Steem are always attached to money transfers. It always costs a minimum of 0.001 STEEM or 0.001 SBD to send a memo to someone. It's a pretty effective deterrent against memo spam. IMPORTANT! If you want to send a private memo, the '#' character needs to be the first letter of your memo on Steemit. Other front ends may have a checkbox you need to check if you want to encrypt a memo you're about to send.
The private posting key exists for you to be able to make a post or a comment or to claim rewards.
The private active key exists for you to be able to transfer tokens to another account, to power up or power down and to delegate or undelegate powered up tokens. You need the private active key to use the internal markets on Steem and on Steem-Engine as well.
The private master key can be used to sign any of the above transactions and to change any of the keys or the master key itself. All the other keys can be derived from it. In case your master key is stolen (and subsequently changed) it can be recovered. When your account is created, an account recovery partner is defined for that purpose. It requires their signature for you to change the password - and yours with the old password. IMPORTANT! But if you have lost your master key, your account is beyond recovery and gone forever. This is why you should never lose your master key and also keep it offline as much as possible. Make encrypted copies of your master key and store them at safe locations (and do not lose the encryption password). A password manager such as KeePass is good for that purpose.
Steem Keychain is a browser extension/add-on available on Chrome Webstore. You should absolutely use it. You'll never have to insert your private keys into any websites that have integrated Steem Keychain. What they do is they ask Steem Keychain sign all the transactions and broadcast them to Steem. Steem Keychain stores your keys locally on your computer safely in an encrypted file. Steem Keychain does not store your master key.
If you have any questions, please do ask them in the comments.
