I'd like to learn more about mining Monero and I heard about smart mining.
How does 'smart mining' differ from regular mining? What are the trade-offs involved?
Smart mining is the process of having a throttled miner mine when it otherwise does not cause drawbacks. Drawbacks include increases heat, slower machine, depleting battery, etc.
As JustinEU4 mentioned, the intent of smart mining is to increase network security by allowing as many people as possible to let the smart miner on all the time. For this to work, the miner must prove unobtrusive, or it will be turned off, depriving the monero network from a little bit of security. As such, it is likely that a smart miner will miner more slowly than a normal miner on the same hardware.
Smart mining was started in 2014, but the contributor had to leave due to lack of time. The current code is at https://github.com/oranjuice/bitmonero/tree/smart-mining.
When this is finished, it is hoped that the relative slowness of a smart miner will be offset by the large amount of people running a miner for a possible "lottery win", and thus increase the monero network security by a non trivial amount.
"Smart mining" is a proposed implementation of normal mining that is currently under development. Basically, the intention is for a computer to automatically mine in the background when not in use (like BOINC). This will help keep the network decentralized and increase the hash power. "Smart mining" does not make your computer mine faster.
Monero release 0.10.2 added initial support for smart mining on Linux only. As the feature gets more testing, it is expected to spread to other platforms and be used more often.