Why after connecting the bootstrap table styles change?

Question

Explane me please why after connecting the bootstrap table styles change. Below is the connection tag.
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">

Answer 1

//Because bootstrap has its own default style for all html, maybe that's why table style got changed

Answer 2

Thanks for the answer. Then why drop styles with a reset.css. Or is it not necessary when connecting the bootstrap?