One’s pants would be called breeches or hose, and for the most part ended somewhere above or directly below the knee. All varieties should also have pairs of eyelets about the waistband for tying to the doublet. Waistbands and leg bands were usually narrow; between one to one and one half inches wide where applicable. Some types might have a button fly, others might have a pair or two of laces, and others might feature the legendary codpiece. Interestingly, pockets were beginning to be worn set into the side seams or hips of the breeches and were quite large.
Materials varied per type of breeches. Any sort might be made out of some kind of wool fabric like flannel, worsted, broadcloth, kersey, say, serge, or frieze, but it appears that Venetian Hose ( described below) seem to have had the added bonus of linen or hemp canvas, leather, or fustian. Of course silk taffeta, satin, velvet, and so on were possibilities for those who were permitted to wear it and/or could afford it. Types of buttons were generally the same as those on doublets. See that section for more details.
This sort of hose went by many names including Paned Hose, Paneled Hose, Roundhose, Scaling Hose, or Sliding Hose to name a few, but Trunkhose seems to be the most common, or at least accepted, term. Many people in the present refer to them as Slops, but I have always associated that name with the sort of breeches worn by sailors. Trunkhose were worn throughout the period, and changed from time to time in their shape; At some points the shape of each leg resembled globes, other times pears, and so on, so be careful to note which shape is appropriate for your time and place. Throughout all, they never ended lower on the leg than the mid thigh, and could be much higher. Some extreme examples show them ending just below the crotch.
They were also always very full and rather bulky. This resulted from both the waist and leg measurements being several times larger than the wearer's actual size and then being gathered or pleated in and sometimes some kind of padding or stuffing. This stuffing might be called bombast and would be made of wool, flax, or cotton fibers, hair, or bran. They could be paned (having several vertical strips around the perimeter of each leg with a decorative lining showing through as above) or unpaned. Trunkhose might have close fitting extensions (almost like bike shorts in shape) called Canions that ended just above or just below the knee cap. Canions could be of the same or a visually-related material as the rest of the hose and one's stockings would be drawn up over them if they were being worn rather than under. Having Canions on unpaned Trunkhose before the 17th century seems to have been less common for Englishmen, but unpaned hose with them do pop up here and there after the mid-1570's.
Trunkhose could have codpieces or possibly inconspicuous buttons or a few pairs of eyelets. Note the size of the codpiece in the picture above. It was only in the early 16th century that codpieces were gargantuan, and by Elizabeth's reign they were around this size or perhaps very slightly larger if that. In fact, they were going out of fashion and after the 1570's they are very rarely seen. By around the last decade and after they are not seen at all. It should be noted that codpieces were not meant to hold anything, and were solidly stuffed or padded into shape. They were only supposed to suggest virility, not contain it.
Venetian Hose or Venetians first appeared, perhaps unsurprisingly given their name, in Italy in the early 1550's. They first showed up in England in the mid-1570's and continued to be worn there well into the 17th century. They were very full at the waist where they would be gathered or cartridge pleated into the waistband, and tapered down to the knee where they would have no leg band. They did not have codpieces, and instead had button flies that were not too dissimilar to those we have today.
They might fasten at the very bottom of the inseam with a few pairs of hooks and eyes, or on the outer seam with a pair of eyelets and ribbon or with a couple of buttons, though the latter option seems to be one of the least-represented in primary sources.
Galligaskins or Gascon Hose were very full breeches, perhaps not unlike Trunkhose, that were gathered into the waistband and legbands but ended directly above the knee. They might have had a buttoned fly or possibly a codpiece, but there are not many surviving images of what are probably Galligaskins. The term might also describe the full breeches that end below the knee that came about closer to 1600 as well as possibly very very large pairs of Venetians.
I am still looking for more information on this sort of calf-length breeches, but their use, at least in England, seems to have been less than frequent. With the exception of one countryman playing a drum, they appear to have been worn only by sailors and mariners (though these were not the only sort worn by them). It would also seem that they were more common amongst the Dutch, who also had a variety with the ends of the legs pointed like a triangle at the front and back. Linen or hemp canvas or possibly wool are the likeliest materials. Besides large, loose breeches associated with sailors, Oxford English Dictionary also associates the term with a loose coat-like garment, while conversations with others have suggested that slops could also refer to garments remade or pieced together from existing ones. In later periods (and perhaps earlier as well), slops becomes associated with cheaply-made clothing, particularly for service at sea.