Sophos has been around a lot of years and while well respected in the business world they've generally not been know to the home user. Why, simply because they have concentrated on the business and education market. Sophos Home sees them starting to offer free versions of their software to the home user, yes there is a catch, there is limited support, but that's the same with most free A/V.

Home offers up to 10 devices protection and they can be any mix of OS's.

And before anyone says "never heard of them" look at enterprise or business AV rather than consumer, its generally not in many home user charts as they've traditionally not been targeting that area.

They also offer the XG firewall (needs to run on a dedicated or a virtual PC) as well as a software based Threat Management Gateway. Both of which are much more akin to business grade devices than home, most people won't need either but they are free, yes there are limits but pretty sensible ones mainly to stop the software ending up in a business, after all they are a company and need to get paid somehow. It can also help filter web sites, stopping malware, or acting as a level of parental control, controlling Web access and stopping little eyes seeing inappropriate content.

Why do they do it, two fold, the more protected devices around (by any AV) the more everyone is protected, if you don't have malware your not going to be spreading it, and secondly because like every AV vendor they get samples from a wider audience, so they can respond faster and protect their paying customers better.

I'm Just a happy user, I use Kaspersky on the PC's and Sophos and AVG on the Sophos web gateway, everything should e scanned by at least two different A/V products to try and keep malware out my PC's.