Bitcoin transaction fees are included with any Bitcoin transaction so that it can be validated by a Bitcoin miner which then in turn gets the transaction confirmed on the blockchain. Once a transaction is confirmed on the blockchain, it is irreversible. Transaction fees are part of the incentives for miners to mine the Bitcoin blockchain. The other part of incentives for miners is the block reward for each mined block.
Bitcoin is made up of transactions which fill blocks, which then get chained together, forming an immutable blockchain. Each block processed takes about ~10 minutes. For example, to process 6 blocks takes about an hour on average. Typically, most people using Bitcoin as a currency don't want to wait many blocks for their transactions to be confirmed, so they pay next block fees to get their transaction confirmed within 10 minute block times. Median fees are just the middle range of all the fees to give users a better idea of the average amount being paid by everyone, discarding high and low fees. The median fee listed is based on the past week of transaction data. Median fees are also provided here in JSON format: export historical median fees.
Bitcoin Core (BTC) fees are much higher due to a limit on block capacity. The block space available for transactions on the BTC network is currently limited to 1MB. This means that transactions on the BTC network during times of congestion can skyrocket up and become very expensive as people try to outbid each other to try to get their transactions confirmed. BTC originally wasn't designed in this way, but was changed later by Core developers to change BTC into a settlement system. Bitcoin Cash (BCH) transaction fees are much less as the block space is not limited to a low capacity. BCH has scaled onchain allowing for a lot of extra block space for adoption and low fees while still retaining the original Bitcoin attributes.
Thanks to a few API providers, BitcoinFees.cash was able to blast off. Next block fee data is provided by BitGo, median transaction fee data is provided by Blockchair, Bitcoin price data is provided by CoinSalad and the chart is provided by AMcharts. Imagery by Kurzgesagt. All live fee data is updated every ~10 minutes and charts are updated weekly. All fees are priced in dollars. Disclaimer: The fee amounts shown on BitcoinFees.cash are for informational purposes only and due to the decentralized nature of Bitcoin the fees shown are probabilistic and there are no guarantees that they will work.
Bitcoin Cash is Bitcoin, just like how Bitcoin Core is Bitcoin. Both are conceptual ideas that have brought the world a new idea of money. However, Bitcoin Cash aims to follow the original ideas of Bitcoin in being peer-to-peer electronic cash. In doing so, Bitcoin Cash developers have been working hard to make BCH the best money in the world. You can support BCH by supporting websites like BCH.info, Bitcoin.com, BitcoinCashers.org and many others. Watch this video for a crash course on BCH. If you like BitcoinFees.cash, visit my other site BitcoinPrice.WTF for a Bitcoin Cash price calculator!