Full form of SIP is Systematic Investment Plan

A Systematic Investment Plan (SIP) is a mechanism of investing money in which a certain amount of money is periodically invested in a financial instrument such as mutual funds, gold, etc. The investing frequency can be weekly, bi-weekly, monthly (most popular), quarterly, etc.

It is recommended that one should start their SIP investing journey as early as possible to reap the most benefits out of the compounding effect (i.e., interest on interest). For a detailed analysis of the gains you could get from a disciplined investing approach, you can use the SIP calculator available at SIPCalculator.org