According to a recent study by U.S. job site Glassdoor, there are 263,586 unfilled technology jobs in the U.S.

In 2015, the White House cited an even higher number, 545,000, based on information from Burning Glass Technologies, a labor analytics firm that analyzes help-wanted ads.

Whichever study you look at, technology is changing quickly, and the tech field is changing along with it. It’s changing so fast, though, that positions like software engineer, data scientist, Java developer and others are being left empty.

Those lost jobs aren’t just hurting employees and employers. They affect the overall economy.

According to Glassdoor, unfilled tech jobs led to $20.1 billion in lost productivity and earnings. When jobs go unfilled, businesses aren’t able to produce as much and consumers don’t have as much to spend and invest.

But if vacant jobs are so bad, why can’t tech companies fill them?

1. The Skills Gap

Perhaps the biggest reason for the mismatch between jobs and new hires is the skills gap. As our economy becomes more high-tech, so do job requirements. Qualifications, however, haven’t been keeping up with that trend.

As businesses and manufacturers introduce more advanced technology into their processes, they lay off lower-skilled employees. Those people don’t have the training to work in a high-tech environment. So many people have been laid off that there aren’t enough people with a technology background for the new jobs.

2. More Jobs

The technology industry is growing rapidly; too rapidly for workers to acquire the necessary skills to fill new jobs. This large amount of new jobs means some of them stay open. Some job postings may either remain open or be in continuous demand simply due to the industries they’re a part of. For example, positions in aerospace and engineering are likely to be continually hiring, because the tech associated with these fields is constantly developing and improving.

While this is good news because it means the tech industry as a whole is doing well, it also means companies could lose out on productivity as they embark on the long search for qualified workers.

3. Job Location

Another theory for why the skills gap exists is that available jobs and people with the right skills are in different geographical areas. It’s possible that skilled employees and tech jobs aren’t able to find each other because they’re too far apart.

Additionally, tech jobs are usually located in cities, many of which have a high cost of living. Recent college graduates or other job seekers might not have the necessary resources to make that move.

4. Education Bias

Another contributing factor may be that employers are increasingly looking for recruits with more and more education. Employers may need the skills that education would provide, but employees with both a higher degree and the proper skill set could be hard to find, especially since education hasn’t quite kept up with the technology boom.

According to a survey by job search engine CareerBuilder, 37 percent of businesses said they now require college degrees for positions that in the past only required a high school diploma. The survey also reveals 26 percent of jobs that previously went to people with bachelor’s degrees are now reserved for those with master’s degrees.

The reason for this change, they said, was that the jobs had changed and now required more skill. Employers looking to fill positions in research-heavy fields may be more likely to value higher education, even for lower-skilled roles.

Solutions for Employers and Employees

Although there are various probable ideas about why we have a tech job gap, we can only theorize. Another crucial and perhaps tougher part of this hypothesizing is dreaming up possible solutions.

The solution thought up by Google and online education company Coursera is a boost in tech education. The two companies partnered to release a new set of online courses about data engineering on Google Cloud. More scholarships and more courses in all levels of education could be a smart first step.

Other possible answers include spreading out locations of tech companies, making them more accessible and using online services, such as job search sites, to connect job seekers with employers no matter where they are.

The tech field is an exciting place to be: the pay is high and there are plenty of jobs available. Lots of people don’t have the necessary skills, though, for high-tech jobs, and those who do often have trouble finding or accessing them.

To help close this gap, we should invest more in technology education for everyone — from young kids to adults — and do more to help connect workers with tech opportunities.