How do i keep updated about the digital marketing field or what are the most important magazines and websites should i follow?

There are many websites out there to keep you updated with almost everything in relation to digital marketing. The following websites will help you to learn and also keep you up-to-date with developing trends; (To find what you are looking for, make sure to visit blogs within some these sites) (There are millions of good sites out but I am going to share a few). Hope you can find good updates from the sites below.

1. http://www.jeffbullas.com/
2. https://econsultancy.com/
3. www.Moz.com
4. http://searchenginewatch.com/
5. http://www.briansolis.com/
6. http://www.kaushik.net/avinash/
7. https://www.gartner.com/user/registration/prospect?resId=&srcId=1&pcp=gi&cm_sp=GI-_-RR-_-ABOVEFOLD

Mr. Stanely and Mr. Usman both provided great list of websites to follow. I would like to suggest below.

- https://www.searchenginejournal.com

- mashable.com/category/digital-marketing/

and the most important is LinkedIn , Follow digital marketing experts , professional & Companies to learn digital marketing.

One clever way to keep up to date on lots of thngs including social media tools is to track what tools they are using at world class exhibitions eg CES.

My friend Stanley has given a very good list of sources.I would like to add:

1. Sprinklr Blog
2. Gary Veynerchuck
3. Social Media Examiner
4. Marketo whitepapers
5. HubSpot whitepapers
6. GroupHigh blog
7. Shoutlet blog
8. Poynter Institute

Unfortunately there are not enough magazines or websites to follow for digital market. Yes webpages can help but not quality wise. 

You can ask someone to trade Digital marketing  books.