Most platforms will let you buy funds, shares, exchange traded funds. And you can also decide whether to put these investments in a trading account, an ISA or a DIY pension referred to as a SIPP.
The other benefit of most investment platforms is that these days they have helpful tips and pointers for those of us who don't have the foggiest where to start or what to pick.
Most will have fund shortlists, and research analysts will have compiled their top picks. If this is still more choice than you want, many offer ready-made portfolios. A sort of Blue Peter here's-one-I-made-earlier.
The rather packed chart on the left gives you an at-a-glance list of what each provider is offering.