In the past, fees have been different from today. You can send a free transaction if your transaction is small or if it is "preferred". However, now everything has changed and every transaction is required to pay a fee if it wants to be confirmed. Charges are measured in Satoshi per byte. Think of taking Satoshi (the smallest unit of the Bitcoin account), multiplying by the number of bytes (unit size). At any time you can also check the estimates for your transaction fees in the next block. This rate varies depending on whether the network has many transactions. But transaction size depends on a number of different factors, the most important factors are: Number of inputs, Number of outputs, Scenario is more complex when some transactions use special features like multisig. These features increase the size of the transaction.
There are several ways you can avoid paying a high fee:
Avoid sending transactions when the network is crowded, Use a wallet that supports SegWit, Gather input, Gather the output.