A relatively simple concept when it comes to backlinks is the rate at which a website has gained them. This is important to consider for two reasons.
First of all, Google typically favors websites that get a steady stream of new, relevant backlinks. A website that got 100 backlinks 5 years ago and then hasn’t gotten another one doesn’t really appear authoritative, does it? This relevancy also likely means that new content gets backlinks, not just the old stuff.
Second, steady backlink accrual is usually indicative of real, legitimate backlinks. Purchased links usually come in in big batches all at once. It’s very rare for natural links to come in that fast.
Tools like Ahrefs will show you a website’s backlinks over a long period of time, making it super easy to view this metric.
One major thing to look out for is a massive spike of backlinks towards the start of a website and then a steady decline to present day. This is indicative of purchased links that are slowly starting to fall off, get deleted, or get de-indexed. Not good!