A brief history of surface types. (2004-2006)
As many of us are probably aware, ROBLOX started development sometime around mid to late 2003. Throughout the years, ROBLOX has made several revisions of the surface and joint system. From Bumps to Spawn, there's loads of fun!
In 2004, ROBLOX was still getting prepared to make their very early prototype, and I assume they came to a road block. "How shall thou make our legos lego not unlike legos do lego!?!?" Well, the answer became clear. Bumps!
Bumps 2004-2005
Bumps were just Studs in their purpose and Glue in their functionality, except for one clear distinction. They were 3D! Indeed, they were called Bumps, and that was for good reason! Any models using Bumps that are imported into a client which does not support them, have their Bumps automatically converted to Glue.
Smooth 2004-Present
But how does one not make everything known to man a bumpy ride? Make a Smooth surface! Bumps would attach to these Smooth surfaces, and would keep themselves attached until a force is applied.
Motors 2004-Present
Motors existed since nearly the dawn of ROBLOX. They were a simple conceptual solution to a complex problem. How does one make cars go vroom-vroom? Attach some spinny things, wind it up, and watch it go! Motors have existed seemingly since at least 2003 or 2004, being a part of one of the core concepts of ROBLOX, Controller Flags!
Hinges 2004-Present
But what if you don't want to make things constantly spin, perhaps making a door or some other type of rotational pivot that doesn't rely on constant force? Hinges!
Spawn 2006
There used to be a surface named Spawn, this would create Parts from itself. Presumably, it would spawn parts at a regular interval, and not work much like the SpawnLocations of today.
Glue 2006-Present
The renamed replacement for Bumps, works in almost exactly the same way. If you have ever looked inside of the surface setter, you may have noticed it's position in the menu is the second position. Likely meaning Glue replaced Bumps for compatibility reasons.
Weld 2006-Present
Stick two things together, but don't break unless we blow you up! Welds would completely stick two parts together, until they had a joint break called, or were manually broken by a move tool.
Studs and Inlets 2006-Present
These two go hand and hand like bread and butter, one does not work too well without the other. Think of it like the Studs and Inlets of a Lego brick. They pop into each other so you can connect the two! These two will create a joint and will work not dissimilar to a Weld, but Studs can only connect to Inlets and Inlets only to Studs.
It should be noted that, despite what that 2005 patents say, during the time of the Morgan McGuire builds, Bumps and Smooth were the only two surface choices, however, Motors did also exist, under a different drop-down.