There were, of course, many kinds of weapons available. We can only talk in generalities here.
The state of the art at that point for rifles was the repeating, bolt-action rifle using smokeless powder in its cartridges. This meant that a soldier could shoot multiple bullets without reloading (these were not automatic weapons, though). The smokeless powder allowed soldiers to hide more effectively. There were also smaller rifles, called carbines, that were used a great deal in cavalry units.
There were all sorts of artillery pieces. There were rapid-fire artillery pieces like the "French 75" that did not need to be reaimed after every shot. This allowed it to fire up to 15 rounds per minute for long periods of time. This particular cannon had a range of about 5 miles. There were also mortars which could be used to shoot small shells in high arcing trajectories.
Finally, there were some kinds of automatic weapons similar to machine guns. The most famous of these was the "Maxim gun." These were big things that had to be pulled around on wheels sort of like a cannon. They could fire something in the range of 600 rounds per minute.
Of course, there were all sorts of other weapons around. But these were the state of the art in the most important types of weapons before WWI.
There were a variety of simple weapons used before world war one. They included vehicles that had a few abilities of present day tanks and small arms such as rifles and snipers. These weapons developed or you can say evolved over time. Most part of this evolution was during the World Wars. The need for better weapons arise when the opponent had to be defeated. Using the old weapons people made changes and improved them such as tanks. Or they created completely new weapons such as the flame thrower.