A common question, and increasingly so, is relating to using MS Access over WANs (Wide Area Networks – which the Internet qualifies as).
The short answer: Keeping in mind the fact that MS Access uses the Jet/Ace database engine, MS Access simply does not, should not be used in any manner over WANs, wireless networks and/or the Internet.
The longer answer: As with most things in life, there are always ways to bend the rules… As such, there are techniques that permit one to use a database over WANs: the use of Terminal services, CITRIX, which the newer version of MS Access (2010 especially) developing your database as a Web database and publishing it to Office365.com, utilizing SharePoint services. Albert Kallal, an MS Access MVP, has a very detailed post about MS Access and WANs which covers much more in detail the subject, especially the technical reasons: http://www.kallal.ca/Wan/Wans.html.
That all said, even though there are certain work arounds (each having their own set of pros and cons), I always ask my clients the same basic question: ”What is the purpose of the database you are creating?”. If it is an internal business tools (used over a wired LAN network), then MS Access is definitely worth exploring further. If on the other hand, it is to be shared, over the Internet or corporate WAN, with lots of users/clients, etc. then it is time to look at web databases (which Access simply is not – at least not in the standard sense of the term). This is when you have to truly start looking into databases such as: MySQL (very common and cheap hosting is easy to find), PostgreSQL, SQL Server (harder to find host and more costly typically) and development languages such as: PHP, .Net, JAVA, and a multitude of others.
In-house application used over a wired LAN connection-> MS Access is the apex in development tools! It is the fastest and probably easiest development tool used by millions, upon millions of users around the world!!!
An application to be run over a WAN, Wireless Network and/or the Internet -> Turn to more professional web application and development tools.