Safari
Safari is the fastest and most efficient way to surf the web on your Mac. An updated start page includes Favorites, frequently and recently visited websites, Siri Suggestions for relevant websites in your browsing history, bookmarks, Reading List, iCloud tabs, and links sent to you in Messages.
Start searching. Click the Smart Search field at the top of the window to see websites you’ve added as favorites. Or start typing a word or website address—Safari shows you matching websites, as well as Safari Suggestions.
View multiple websites in one window. Click 
at the far right of the tab bar or press Command-T to open a new tab, then enter an address. To keep a website handy, drag its tab left to pin it, and it stays in the tab bar.
See what’s open on each of your devices. You can see open webpages on all your devices that are signed in to the same Apple ID. Just click the Show All Tabs button 
at the top of the window and scroll down if necessary.
Browse the web safely and privately. Safari warns you when you visit a website that’s not secure, or that may be trying to trick you into sharing your personal data. Safari also protects you automatically from cross-site tracking, by identifying and removing the data that trackers leave behind. Safari asks your permission before allowing a social network to see what you’re doing on third-party sites. For example, if you click a Facebook button to share an article to Facebook, Safari asks if you want to let Facebook see your activity on the site. And Safari defends you against web tracking by making your Mac harder to identify uniquely.
When you sign up for a new account on the web, Safari automatically creates and autofills a new strong password for you. If you choose Use Strong Password, the password is saved to your iCloud Keychain and will autofill on all the devices you log in to with the same Apple ID. You can ask Siri to show you your saved passwords, which you can see after entering the authentication password for your Mac, or go to Safari > Preferences and then click Passwords. Reused passwords are flagged in the passwords list, so you can easily replace them with strong passwords.
Note: Siri may not be available in all languages or in all areas, and features may vary by area.
Set up preferences for your favorite sites. If you often adjust settings for certain websites, you can use Safari preferences to save those settings. You can turn on your content blocker, enable Reader mode, allow notifications, set a specific page zoom, and more—just for the websites you choose. When you’re visiting a website, choose Safari > Settings for This Website, or secondary click (that is, right-click) on the URL in the Smart Search field.
Open Picture in Picture. When you’re playing a video, click and hold the Audio button 
on the tab and choose Enter Picture in Picture from the submenu. Your video appears in a floating window that you can drag and resize, so you can watch while doing other things on your Mac. You can also set autoplay options in this submenu. To mute the sound from a video, click once.
Learn more. See the Safari User Guide.