Conscription is the when people at a specified age are forced to do national service by doing basic army training. Some countries conscript everyone, other countries have "lottery" conscription (random name drawn from a hat) and others have selective conscription (officers visiting districts and pick the ones they think are best for the army).
Then there is the volunteer army which is of course people joining the army at thier own will without the need of force.
So which is better? Conscription or volunteer?
People say that by having conscription, it would discipline and improve the confidence of the future generation. It is also one reason to prepare the country for any potential threat/war. In Israel, people serve two years in conscription and if you don't wish to serve in the army, you'll be put in the reserves and continue your normal life. If Israel is to be attacked, the nation can mobilise 250,000 troops in 24 to 48 hours. Countries like Israel, South Korea and Taiwan have conscription to prepare for their uncertain future. Singapore has conscription to not only protect their tiny island (half the size of Los Angeles) but to also fight racism and unite their multi-cultural nation. The United States once had conscription during the Vietnam War and chances were, conscripts were often deployed to Vietnam. To avoid conscription, there were three ways - study full time at University, join the National Guard or escape to Canada.
Conscription does not always guarantee victory. Everyone is different/has different views so a conscript army will have a variety of personnel. This will easily effect the morale on the battlefield. For example, if over half of a platoon were conscripts who were forced to join against their will and are forced to fight in a raging battle, the chances of winning will not stack up. During the Falklands war, the Argentine army used conscripts to fight and many of them were so terrified from the vicious firefights that they ended up sleeping under the rocks until the British forces declared victory. During the Gulf War, many of Saddam's forces were conscripts and after facing the fierce firepower from US tanks, they quickly surrendered.
By having a volunteer army, you'll able to focus and provide more time and resources on the small number which they will easily turn into an elite fighting force with motivation. Barack Obama's decrease in military spending is hoping that the US military will become a smaller but more "flexible force". Big investments in higher quality equipment/weapons and an offer of higher wages can easily attract many young people to join the military like the US or UK.
So what is better? Having one million average trained conscripts or having a few thousand elite, motivated and powerful soldiers? You be the judge.