Discounted cash flow is the canonical equity valuation framework. Project the cash flows; discount each year back to present value at the cost of capital; sum them. The output is a valuation. The math is not the hard part.
The hard part is that the answer is almost entirely determined by two inputs that are themselves estimates: the discount rate (WACC) and the terminal value. Project five or ten years of cash flows, discount them, and you've explained maybe 30–40% of the valuation. The remaining 60–70% is the terminal value — the assumption that after the explicit forecast period, the company keeps generating cash forever at some perpetual growth rate, discounted to today.
Move the perpetual growth rate from 2.5% to 3.0% and the valuation changes by 15% or more. Move WACC from 8% to 9% and the valuation changes by 10–15%. Most DCFs are sensitivity tests on these two numbers wearing the costume of cash-flow analysis.
The honest use of DCF isn't to produce a valuation. It's to produce a range — a band that reflects the uncertainty in WACC and terminal growth, plus the uncertainty in the cash flows themselves. A point estimate from a DCF is false precision. A range that says "this stock is worth somewhere between $80 and $130, and the current price is $95" is actually useful — it tells you the price is consistent with reasonable assumptions, which is different from saying the price is right.
I treat DCFs as thinking tools. The output isn't an answer; it's a frame for understanding what assumptions a price implies.