What is a backlink?

From Moz.com: "A backlink is a link created when one website links to another. Backlinks are also called "inbound links" or "incoming links." Backlinks are especially valuable for SEO because they represent a "vote of confidence" from one site to another."

Are all backlinks created equal?

No. 

Local SEO experts weight in: 
 
What is the biggest problem or misconception about the value of links to local SEO?

"That we still talk about "links" at all. Local businesses should be much more concerned with building quality relationships and mentions of their brand as opposed to links themselves. Google has gotten incredibly good at identifying semantic relationships between entities. IMO they no longer need the "a href" to make that logical connection." - David Mihm, ThriveHive

"Links don't appear to impact the map pack results nearly as much as they impact organic rankings."
- Joy Hawkins, Sterling Sky

What are the most valuable link sources for boosting search rankings for local businesses?

"High domain authority (DA) sites are also less important compared to last year. While many local business clients may be impressed with a backlink on a high DA site, ultimately, it’s better to focus on the local or industry-specific sites that potential customers use. Instead of thinking, "We need links" think about how to build a better local brand. Have you identified who your target customers are and what their interests are? There's a myriad of ways to get involved with the local community that align with the interests of your potential customers. Build a better, local brand." - Blake Denman RicketyRoo

"A business should be genuinely concerned about and involved in their local community. Beyond a typical sponsorship, a business may be able to utilize its skill set and resources to help local non-profits with specific needs they have. It should also be a priority for the business to be a true expert in their industry. Their website can help convey this by providing quality answers to questions potential customers are out there searching for. - Tom Waddington Wachae

"The mindset to have when doing local link building is the "get by giving away" approach where there's never any clues or hints about your hidden agenda. Give to the community and neighboring businesses with authenticity and you almost never need to even ask for the link." Steve Wiideman, Wiideman Consulting Group

If a local business asked you how many links they should aim to get each month, what would you say?

"Firstly, it's not about volume, it's about quality, particularly for local businesses. Secondly, it completely varies by category. In a non-competitive space like a long-tail machine parts manufacturer, a couple of quality links a year could make a meaningful difference to their business. In a hyper-competitive space like personal injury law, those firms should probably be aiming for a half-dozen to a dozen high-quality links per month." - David Mihm, ThriveHive

"It varies greatly based on the industry. We have some clients that only really get a handful of [good] links a year and do really well with that. Others are stacked up against competitors that have hundreds of linking domains." - Joy Hawkins, Sterling Sky

"Don't get too caught up in numbers. 50 directory links might not be as powerful as one sponsorship link. It's really about quality over quantity with link building. Aim for links that your competitors will have a hard time getting on highly authoritative pages." - Casey Meraz, JurisDigital

"Focus on the question, "Will getting more links build the quality traffic to my site?" - Ben Fisher, Steady Demand

How valuable are the following strategies when building new backlinks to local business sites?

Building relationships with local businesses and influencers (#4 last year)
Creating research-based content (#5)
Sponsoring local charities and organizations (#1)
Creating resources with a local focus (#3)
Hosting community events (#6)

Where do I get local backlinks?            

1. Sponsorship of local community events    
2. Sponsorship of local local teams    
3. Local bloggers who you can contribute content to or who may want to write about you.    
4. Local clubs or organizations you and your employees belong to i.e. church groups, exercise classes, car clubs. If you or one of your staff are in a leadership position all the netter. Find out if you can contribute content or if they have a business listing page.
5. Neighborhood watch sites sometimes have a website or blog. Find out if you can contribute content or get listed in some manner. 
6. Local vendors. 

Websites usually a contact person or webmaster listed. Unless you are sponsoring an event, reach out to the contract person to see if you can contribute content or they may simply have a section where you can list your business information. 

Should I get backlinks from national or non local directories?        

Yes as long as the backlinks are in directories Google would expect you to be listed in such as for the ADA, AGD, state and local dental associations, etc.        

What is the bottom line on backlinks for a local business?        

The bottom line is only obtain backlinks from sites where visitors to that site are potential patients.