A tipset is a set, rather than a chain, of blocks that make up a blockchain.
A tipset is a term mostly used to describe the blockchain of decentralized storage system Filecoin. Filecoin’s consensus mechanism is built on tipsets, as their Expected Consensus system (unlike Bitcoin) is election-based and allows for multiple miners to be the elected leaders in a round.
This means that Filecoin (or another similar storage system) allows more than one storage miner to create blocks in one epoch, which in turn increases the network throughput. Basing a blockchain on tipsets can also contribute to the security of the network: simply put, since each tipset’s weight is relative to the amount of storage it provides, any node that attempts to disrupt the creation of valid blocks must contend against the consensus’ preference for heavier chains.
The advantages of using a tipset system are that miners will gather together to support the heaviest chain, or the chain that is creating value — this is because decentralized storage systems naturally prioritize chains that are offering more storage. Tipsets that are lighter chains become orphan blocks, since they don’t have the draw of greater storage power.