A Web Browser is a program or App which allows you to browse websites on your computer or other internet enabled device. Your device or operating system will have a default (go to) browser set right out of the box, for example Microsoft Windows 10 uses "Edge", Apple MacOS Sierra uses "Safari", and Linux Ubuntu uses "Firefox" ...BUT ...The bowser you use is ultimately up to you, you can choose from the browsers available to your operating system. My personal favourite browser on the Mac is Safari, and on a PC I find Google Chrome to be quite nippy.
The Search Box, or Address Bar. Usually the Address Bar and Search bar are unified nowadays, in other words you can enter a direct URL such as "cpwiz.co.uk (Uniform Resource Locator - Web Address 😏) into the bar or a search phrase such as "Computer Wiz".
Home Button, this pretty much does what it says on the tin... Click the button and wherever you are on the web you'll be taken back to your home page faster than Mr Spock can beam from the Starship Enterprise to the alien planet below.
Back & Forward Buttons, this is how we navigate backwards and forward through web pages on the internet.
Tabs, probably one of the best modern browser innovations. Tabs allow multiple web pages to be open at once in one browser window. For example you could have hotels for your holiday up in one tab and flights and car parking open in other tabs. Open and close tabs as you need them.
Favourites or Bookmarks Bar, (named either, let's go with bookmarks bar) keeps all your bookmarks accessible at the top of your browser window.
That's covered the basic features common to most browsers, the browser you finally decide to settle with will probably be chosen for it's key features, for me I prefer Safari on the Mac because my favourites sync across all of my devices and I love the "Reading List" feature which is kind of a temporary bookmarks feature. See my post on Eco Systems.