Computer

Computer is a tool that consumes items and gives you Research (depending on the price of item). Items with higher rarity give significantly more Research.

Computer accepts any item except containers, blocks or liquids.

Computer requires a small amount of Power: 40J for every 100 Research. For comparison, burning 1 Wooden Log in Alternator Generator also gives you 40J.

How much Research do you get
Each computer has "conversion rate". For example, for Personal Computer it's 1%.

If the items you spend have a total price of 10000 pixels, then you get 100 Research (1% of 10000) if they are Common, 115 if they are Uncommon, 125 if they are Rare or 150 if they are Legendary/Essential.

Hi-tech Precursor computers (that you will eventually find) will also produce some Ancient Essence in addition to Research.

List of computers
The following objects are Computers (from worst to best):
 * Basic Computer (1%, 10 seconds) - these numbers mean "amount of Research that you get is 1% of pixel price, and it takes 10 seconds to process 1 item".
 * Personal Computer (1%, 2 seconds)
 * Advanced Computer (2%, 1.5 seconds)
 * Research Server (3%, 1 second)
 * Research Mainframe (6%, 0.5 seconds) - warning, this building is REALLY HUGE (needs a lot of space to be placed), so it might not fit on your existing base.
 * Precursor Data Box (4% Research, 0.4% Ancient Essence, 0.5 seconds) - not craftable, but you can find them in underground Precursor biomes.
 * Precursor Mainframe (6% Research, 1.2% Ancient Essence, 0.5 seconds) - warning, REALLY HUGE building.

Good items to research
Randomly generated weapons are often a good choice, because they have decent rarity.

Another option is to look at your chests: surely you have some leftover Common materials that you don't need, and they can likely be crafted into something Uncommon or Rare.

Cooked foods (from Kitchen Counter) may be good: they are often (but not always) more expensive and/or rare than their ingredients.

If you organize something that earns you a lot of money (plant farms, automated factories, liquid mixing rigs, breeding superior bees, etc. - dozens of ways for all tastes), then you will never run out of Research.

Bad items to research
Throwing items of Common rarity into computers is often a waste. You might want to look into what can be crafted from them.

Items that are very cheap are not a good choice: you will need several of them to produce 1 Research. Items with price 0 are the worst (it takes 1000 of them to get 1 Research).