Use of bootstrap and other sources are good practice or not for web designing?

Question

what i mean to say is these are some plantform which provide pre designed buttons and input fields and many other . so just copying these files and making web page is a good practice?

Answer 1

Learning bootstrap is a must for every web designer/programmer as it makes layout and inclusion of css sytles much easier and quicker. Nonetheless, it is very much important to understand the underlying html, css and javascript(jQuery) concepts, so you can always alter the defaults codes if the need be.

Answer 2

means we can use bootstrap and alter the codes as we need. But publishing the website using bootstrap doesnt leave a bad impression since every sites has its own css and javascript. thats why i asked the question.