If your resume looks strong, why would a LinkedIn profile even be necessary? For a few reasons.
Some companies search for future employees or look to fill specific spots through LinkedIn before they actually post a job or while they're interviewing. In this respect, a LinkedIn profile acts as a kind of resume. At it's most effective, your LinkedIn profile contains all your professional experience, updated and accurate, with some personal spice sprinkled in. The first few lines of your profile are actually the most crucial—name, title, and most recent positions. Those three parts show up in a LinkedIn search, along with your photo. So, consider adding a recent and clear picture of yourself.
Your LinkedIn profile might be the first professional impression someone has of you. Even if you don't join groups or actively search for a job, LinkedIn profiles are searchable on Google and Human Resources departments do actively look. Sometimes, so do executives. In fact, many companies are now looking up Facebook and LinkedIn profiles to see what kind of information is posted about a candidate before they hire. Post carefully.
It is estimated that more than 300 million people worldwide now use LinkedIn. If you are in the market for a new position, you might want to consider the implication of hundreds of thousands of employers looking to fill jobs. If so, your LinkedIn profile would be found well before you presented a resume. If a recruiter likes the information in your profile, the resume may be only a back-up piece to verify your past.
More information about you
For some people, LinkedIn can serve as a personal website. But just like with a resume and cover letter, you have to know how to optimize the contents to make it work for you.
LinkedIn is actually set up a lot like a resume; there's a title, summary area, positions are listed chronologically, and there is room for awards and memberships. As with a resume, you can use beneficial, descriptive words. Go ahead and cut and paste information directly from your resume to LinkedIn. Just don't use bullet points—they won't translate. While LinkedIn is more casual than a resume and you could use adjectives such as passionate, organized and communicative, remember, LinkedIn profiles are searchable. Personally descriptive words will not help you. No recruiter ever searched for “passionate engineer” or “results-oriented” anything on LinkedIn.
You benefit from the details
Make sure your profile photo is a professional-looking headshot. Don't post a picture with your cat or in last year's Halloween costume. Leave those for Facebook and Twitter.
For the experience area, pull specific information straight from you resume. If job descriptions are too long, just add your accomplishments. As with you resume, use a lot of industry words in the context of your experience. Those are the searchable words.
LinkedIn is a great place to add personal details that wouldn't normally be appropriate for a resume. Hobbies, professional organizations, school clubs, and non-work certifications give an interviewer more personal information about you that can be used as conversation starters. Some executives have been hired because a recruiter saw that someone enjoys mountain biking or is a Red Sox fan and the conversation went from there.
Think of LinkedIn as another job-seeking tool, in addition to a resume. Some LinkedIn members put their LinkedIn address on their resume. LinkedIn is the most formal of all the social media platforms, but it is more conversational than a resume. Feel free to add (appropriate) information about yourself that really says something interesting about you.