A staking pool is a group of coin holders merging their resources to increase their chances of validating blocks and receiving rewards. They combine their staking power and share the rewards proportionally to their contributions to the pool.
Setting up and maintaining a staking pool often requires a lot of time and expertise. Staking pools tend to be the most effective on networks where the barrier of entry (technical or financial) is relatively high. As such, many pool providers charge a fee from the staking rewards that are distributed to participants.
Other than that, pools may provide additional flexibility for individual stakers. Typically, the stake has to be locked for a fixed period and usually has a withdrawal or unbinding time set by the protocol. What’s more, there’s almost certainly a substantial minimum balance required to stake to disincentivize malicious behavior.
Most staking pools require a low minimum balance and append no additional withdrawal times. As such, joining a staking pool instead of staking solo might be ideal for newer users.