A portfolio is the complete collection of all the financial investments you hold, considered together as a whole — this can include stocks, mutual funds, bonds, fixed deposits, gold, and any other investment assets you own, across all the different accounts and platforms where you might hold them.
Looking at your investments as a single, unified portfolio, rather than as separate, disconnected holdings, is important because it lets you assess your overall asset allocation, diversification, and risk level accurately. Two investments that look fine individually might together create an unbalanced portfolio — for instance, being overly concentrated in one sector or asset type — something you'd only notice by reviewing your complete portfolio together, ideally at least once or twice a year.
A simple, periodic portfolio review — checking what you hold across all platforms, how it's allocated, and whether it still matches your goals — is one of the most valuable habits an investor can build.