Google recommends that users choose the Orginal option if you own high quality photos from a DSLR.
The photos that you store in the Google Drive store will also appear in Google Photos by default
You can also use the application to automatically upload photos from smartphones, tablets, Windows computers .
When uploading images through the website, you should store them in High Quality mode unless they are taken from a DSLR or you are willing to pay for additional storage.
To view photos, simply visit the Google Photos for Android or iOS website or app. You can move through the photos and touch them for a quick look. Photos will be sorted from new to old. In addition, Google Photos also has a search function, for example you find the word "dog" and you will see pictures that Google thinks it contains that keyword. You can also search for places and locations where you have taken photos.
For example, when you click on the search bar, you will see a list of different people, Google does not know who they are, it only knows the face in the same image and the location of the image was taken, creating favorable conditions to appear similar images.
If you want to arrange photos in the traditional way, you can use the Collection option.
Because Google Photos is no longer integrated on Google+, it has great sharing features. Sharing is as easy as viewing photos just by clicking the Share button at the top of the frame and selecting different options.
You can share photos on Facebook , Twitter or Google+ . You can also click Get Shareable Link to get the link directly to the image, then send it to others by texting, email . and they can view it without logging in.
Google Photos also allows you to download photos, download 1 time / pcs or download the entire picture with Google Takeout . It is also integrated with Google Drive, photos you take on your phone can be automatically uploaded to Google Photos and downloaded to your computer using Google Drive, like Dropbox and OneDrive.
Good luck!