The typical thing I've seen is 1/4 of your options will vest after 1 year, upon which 1/48 of your options vest every month thereafter. Other companies may do it differently.
Also if you leave the company early, you will usually have to pay some trivial amount (possibly thousands though) to keep the options.
This has at least been the case at all startups I've seen.
With the 1-year cliff in place, I'd rather options just be given to departing employees, as it seems like payment for their work.
The vast majority of new option grants for VC-backed companies are under the 1/48 monthly with a one year cliff.
More companies are now switching to converting ISO grants to NSO after you leave a company, and allowing a longer term to exercise. Pinterest famously allows, in some cases, employees to have up to 7 years to exercise vested shares after leaving [0]. Most companies do not do this (yet). Exercising an ISO grant can be much more favorable taxation wise than exercising a non-qualified NSO grant.
If you give shares to an employee, it will likely be a taxable event, as the IRS sees this as taxable compensation.
Also, most grants are at non-trivial strike prices. If you're a super early employee, you might have grants at a very low price, usually a few cents. However, the vast majority of grants are at much higher strike prices where exercise costs are processed in the tens to hundreds of $thousands.
Exercising and taxation are a difficult topic that very few fully grok.
If you're likely to hit AMT, the difference isn't as stark. It can be really easy to hit AMT especially if you've been at a firm long enough that your strike price is considerably lower than the current fair market value (latest valuation).
NSO also has a few other downsides. For employees, when you exercise an NSO, you actually have to pay tax at the time of exercise - the company withholds it and reports it as ordinary income tax (pay taxes in addition to the cost to exercise).
ISO grants can also have horrible tax implications, but you at least get a bit more flexibility as an employee -- this is also why November/December tend to have a disproportionally high number of exercises, as people get a full picture of their potential AMT liability caps.
When a company's valuation is skyrocketing and liquidation is highly likely (IPO or other M&A event), you'll often see companies offering early exercise, which can help avoid huge AMT hits, so employees are exercising when their strike price == the company's current fair market value.
often much more than thousands -- I've personally spent $12k in strike price alone, not to mention the potential tax implications which can be ruinous if you aren't careful
Don't options typically vest after one year of employment? Is that "too far in the future?"