Online history archives are websites that store historical primary resources electronically that can be accessed by the internet. They offer historical data to academics as well as regular people who are doing personal research. They allow easy access to lots of information, people can access information from all over the world, whenever they need it. This is excellent for scholars who would otherwise have to travel to the location of the archives, which is not only time consuming, expensive, but also damages the environment. It also encourages regular people to research as the information is so readily available. If the information is easy to access then people will be more encouraged to do research than if they had to travel to get any information. There are many different sites, which can focus on specific information, The Darwin Correspondence Project focuses on Charles Darwin. Other sites have more broad information such as acestory.com focuses on familial ties or Medici Archive Project which focuses on the humanities.
Limitations are that sites only have certain types of information based on the topic the archive focuses on. Another draw back is that some for profit, such as ancestory.ca require a fee in order to be accessed. While there is plenty of information that has been uploaded, there is still plenty of information that has not been uploaded online. This is due to the fact that not everyone wants to allow public access to their work. A lot of work has to go into uploading the information, and storing it.
All in all, I think they will be great resources, however this is only the beginning so a lot more work has to go into understanding how to better use them. Once they are fully understood they will be a great resource to everyone, scholar or not.