If you are a GMail user, keeping a Google Contact list is essential and having all your contacts easily available makes life much easier. You can always open Google Contacts and manually add a contact, but there are much easier ways.
Save a contact from an email
With Windows, open a Gmail message and hover your mouse over the email address in the "to" addresses or "copy" addresses, then click the little icon with a plus sign next to a person to add that contact to your contact list. Edit to add more detail on anything you want to remember about this contact.
Adding multple contacts at the same timeRead More.
You can also add multiple contacts at the same time. Open an email with, say, a long copy list. Click the down arrow so that you can see each email address.Then select and copy this list including both names and emails. Open Google contacts, and select "import" in the left hand panel. Choose the option "create multiple contacts", then paste this list there. Hit create and all the emails will now be in your contact list. Now click "Merge and Fix" to see where you now have duplicate contacts and merge together any duplicates.
If you have a CSV file with names and emails, you can just import this file directly, using the "import" option again. if you have first name, last name, and email identified, Google contacts will create a contact for each line in the file, with any additional columns in that files being added to the "Notes" field on the contact. If you have say, a PDF file, instead of a CSV file, you can use the PDF export option to convert to a CSV. If you only have a PDF reader and not the paid PDF editor, there are free programs that allow you to convert. Zamzar Online File Conversion offers free options.
Adding Google contacts with an IPhone
We sometimes answer phone calls from unknown callers. For example, if you are waiting for the plumber to call, you probably want to pick up for that unknown caller. With an IPhone, hold down that number in the recent calls list, and then select "Create New Contact". Then just type in the name of the caller, say, "ABC Plumber" and save. The next call from that caller will show up on you phone with the plumbing company name. You must have chosen "GMail" in you Contacts Accounts settings for this to work. You can do the same thing with your text messages.